@smuch that’s so cure, but may be a little impractical 
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Has there been progress on this issue ? Should I ask for a replacement ?
I still love my Kompakt and definitely won’t part with it – but still a bit worried about this symptom.
Issue Update 24th May 2026
Customer support were kind enough to send me a replacement unit on the basis that my previous phone must have had a defective display panel. Poor weather has meant that testing has only been possible over the last few days. Results are provided below. I’ve tried to be sparing in what I’ve uploaded so I don’t saddle the forum under too much content.
Scope
1st party apps and muditaOS
Context
I wanted to test was whether the waveforms infrared (IR) or near infrared (NIR) were the culprit. So, I used a sample of window film produced to reduce these waveforms and others in the solar radiation. (It’s used to keep workplaces cooler.) The film used provides infrared reduction (IRR) of 95%. I’ve provided test cases with and without. If there’s only one result with a shield, you may assume that the result without it was materially worse.
Day 1 (22nd May 2026, 24ºC, sunny spells)
1. Control centre (beneath shield)
1.1 Images
Notice:
(1.1) The time disappears (top of screen).
2. Home screen (no shield)
2.1 Images
Notice:
(2.1) Black cells faded to grey
(2.2) The indicator ‘LTE’ disappears.
Day 2 (24th May 2026, 25 ºC, sunny, clear skies)
4. Maps (No shield)
4.1 Images
Notice: Black cells faded to grey (esp. control buttons)
4.2 Video
Notice: Black cells faded to grey (esp. control buttons)
5. Maps (beneath shield)
5.1 Video
Notice: Black cells faded to grey (esp. control buttons)
6. Control Centre (No shield)
6.1 Images
Notice: Black cells faded to grey (esp. control buttons)
6.2 Video
Notice: Black cells faded to grey (esp. control buttons)
7. Control Centre (beneath shield)
7.1 Video
Notice: Black cells faded to grey (esp. control buttons)
Conclusions
While conducting these tests I was reading on my e-ink notebook device without issue. There is a material difference in the display technology stack used in the Mudita Kompact which means this issue is baked in.
What is affected?
It affects the entire OS, 1st party apps, not just third party apps.
It’s not:
Batch-Related
My original unit was shipped ~May 2025. This unit is from May 2026, so it cannot be batch-related.
UV
Earlier tests showed the same thing happens behind glass, which blocks UV, so it cannot be the effects of UV.
IR / NIR
Using an IR/NIR filter makes no difference.
Next steps
Mudita / @urszula please respond appropriately.
Technical details of shield used.
https://www.tintfit.com/shop/very-light-spectra-67-prestige-window-film
DATASHEET
|Data calculated based on film applied to clear glass
3 mm thick (*on double glazing 4-16-4)|
|| | |
|—|—|
|Ultraviolet transmission|1 %|
|Visible light transmission|68 %|
|Reflection of external visible light|18 %|
|Reflection of internal visible light|15 %|
|Total solar energy rejected|59 %|
|Solar ratio 
|
|Solar energy reflection|27 %|
|Solar energy absorption|36 %|
|Solar energy transmission|37 %|
|Reduction in Solar Glare|29 %|
|g-value|0.41|
|u-value|4.9|
|Rejected infrared (760-2500 nm)|+/- 95 %|
|Shading coefficient|0.4||
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Interesting. Good analysis @petemeister
The Mudita screen has an issue in the sun. I accept that as fact.
Mudita should include sunlight warnings are because the device might not function 100% properly and the users might think their device is defective and call support to complain for a refund.
never-leave-your-phone-in-the-sun
I am not going to risk my expensive Kompakt phone doing similar tests.
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@smuch, you should watch video 4.2 again. Notice the device is locked. (The lock screen de-ghosts the screen.) When it is unlocked pay attention to the rich blacks on the home screen. Within a few seconds, the maps apps is launched and the blacks immediately fade. So, the device does not need to bake in the sun for a long time to see these effects.
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Oh my, that’s unacceptable. Especially considering the GPS works best outside.
I learned something cool watching your video however, on the home screen, the swipe to open apps.
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Thank so much Peter for the exhaustive testing. So my unit is not defective. I wonder why only a few of us experience this, though.
I will live with it. It is still acceptable for me, as long as it does not harm the screen, as the phone is still perfect for my use case.
(I made a test with my Boox Note Max yesterday ; 30 to 35°C and heavy sunlight : no screen alteration).
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@urszula I fully appreciate that there’s probably an uptick in user queries following the roll-out of muditaOS 1.5.0, but it’s now day 3 after the update on this issue was posted and there’s not been an acknowledgement from Mudita. I think those experiencing this issue deserve better. We have seen senior people from the Mudita team post on the forum before and given the gravity of this issue, I would appreciate that here on this topic. Please ask for someone in the exec team to comment here. Thank you.
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Did you reach out to support? I think support handled your original issue. Did you reach out to them again? I can ping them to see what the status is.
I have noticed the fading on my Kompakt as well. It does not happen on my Yotaphone 2 or my Hisense A9. Here in Vancouver, BC, I have been using my phone in the backyard more often. We have had a period of warm and sunny weather. I have noticed that the fading only occurs when UV is at its strongest around noon (when the sun is directly overhead). By 3 or 4 in the afternoon the fading no longer occurs. I don’t think that there is anything that Mudita can do about it. A screen protector that blocks UV rays or shielding the screen from direct exposure to the sun around noon is a work around. I hiked with my family for a week on the West Coast Trail on Vancouver Island last year. The phone worked well. It was hot and sunny the entire week. I did not notice any fading then but I was only using my phone in the mornings and afternoons/evenings.
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@urszula I haven’t reported these updated findings to the support team yet. If you think that is the best way to escalate the issue to senior management, then I’ll do that. I still think a response is required from the CTO or someone equally senior on this issue given its visibility. As others have pointed out repeatedly, other e-ink devices and even other e-ink phones do not suffer from this issue, so something is definitely amiss with the MK.
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I am not sure how helpful this is to anyone but the current UV index in White Rock/Surrey BC is 5. Right now my screen fades within seconds of bringing out into the sun.
I popped outside an hour ago and when I checked then screen was fine. I do not know what the UV index was then.
Covering part of the screen with my UV coated eye glasses prevents that covered portion of the screen from degrading.
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@esquared , thank you. I wish more users would test on their devices so we can begin to see the scale of this issue. However, if you conceal your phone behind a standard glass window (which blocks UV), you’ll see the same effects occur. (This is shown somewhere in my earlier analysis.) So, that rules out UV. Later, I used an IRR (infrared reduction) shield, so that rules out infrared and near infrared (NIR).
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yes, that’s the best way- this way all your previous communication is in one spot & not scattered in separate FORUM posts. I can let them know to expect a message from you.
Thanks @urszula . I’ve notified Mudita support of the updated evidence available on this thread and await their reply. May we take it that the CTO (or similar) will be coming onto this thread to provide their insights into this issue?
Many thanks.
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Average windows block most UVB rays but not much of UVA rays are blocked.
The fading (for me) only occurs when the phone is powered on.
I have two phone displays as I bought a spare screen from Mudita. The spare screen (not plugged in or attached to he phone) does not fade in when exposed to the sun.
If I turn my phone off the screen display also does not degrade in sunlight.
There is anedocotal evidence that heating a eink display controller/thermometer might interfere with the eink display output. Waveshare epaper fades in sunlight when refreshing solved - Displays - Arduino Forum
I heated my phone screen with a hairdryer and it didn’t fade using just heat alone. It was pretty hot to the touch by maybe the heat didn’t get down to the controller. The Kompakt screen assembly is pretty thick with multiple layers.
If the issue is controller chip temperature related maybe Mudita can tweak the firmware to work around this.
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I live at above 7000ft in the Rockies, often sunny…never had an issue with my screen either. Weird.
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Update 20th June 2026: OP here. I’m sorry to say that this issue spelled the end for me and my MK. Not being able to read the screen in the sun (which e-ink devices should be do standing on their heads) was a dealbreaker for me. So, I requested a refund under the 2 year warranty, which Mudita were kind enough to honour. I’m grateful to them for that. And also to the helpful members on this forum from whom I have learnt so much about Android. Perhaps in a few years if Mudita have a mkII with a display that can cope with the sun I’ll be a customer of Mudita again. Until then, all the best folks.
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Hi Pete,
I am sorry to hear this ! Kudos to Mudita for accepting the refund. I really hope Mudita will figure out a fix for this because this is the only major hardware issue with the phone as far as I know.
As for me, I will keep the phone because it is my perfect phone Sure, a slightly better battery or a slightly better speaker would make it more premium… But it is perfectly acceptable the way it is and is the handy dumbphone I was looking forward to for years.
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Sorry to see you go. Good luck on your mindful tech journey.
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