[Samsung Galaxy S20 / S20+ / S20 Ultra Questions & ] scaredy-cat:
Thank you for your answers. Bold text for topics. Testing methods at the end of this reply.

Was not aware OLED screens' image retention is such a common issue, but I knew OLED screens are prone to burn-in, read about it online, and saw it on my relatives' older devices, so out of the box I turned on the

dark mode

and changed wallpaper to black.

I preferred regular Android's navigation buttons to gestures, because of ergonomics, due to phones center of mass (wish it was more bottom heavy), when using with one hand, balancing phone while performing gestures always feels like I'm about to drop the phone, I also find gestures to be slower, simple tap vs sliding your finger. And on top of that, I have carpal tunnel syndrome, so it's much easier to simply reach and tap. But now I started using gestures, as a burn-in preventative measure.

By the way, having Chrome open for around 20 minutes, and quickly switching to Display Tester's BurnIn detection, I can already distinguish Chrome's address bar section, and clearly see tab switcher button. This will gradually disappear, but the fact that afterimage appears so quickly and remains for so long is concerning, since I feel such image retention might indicate my display may be prone to burn-in, but of course, I don't know this for sure, just my uneducated guess.

Having dark mode keyboard open for around an hour, and I can see remnants of it even on grey backgrounds of folders.

Back to reply..

I never use my screen at full brightness, it's always set to somewhere around 50%, and as I said earlier, image retention starts to occurs in a matter of minutes. Images do gradually disappear, but it takes a long time, and when I use screen for hours with static elements, it felt like it took awfully long time to disappear, but to determine how long exactly it takes for them to appear and disappear, I need to do more thorough testing.

Yes, when playing games, indeed, a lot of things are moving, except for Heads-up Display, but I first noticed this image retention issue playing an older video game called "Super Cat Bros". That game is not optimized for such wide-screen phones as S20, so on each side you have a black bar, display is split into 3 sections - bar-game-bar. That game is very colorful and has lots of solid colors, so after I finished playing, in dark user interface backgrounds I noticed discoloration, later looking at solid color backgrounds l noticed clearly where each section was, so bar-game-bar. Because sides of a display were turned off, and all action happened in the middle, you can clearly see which part of the screen was the most active.

This is why I'm coming to conclusion, that dark mode alone is still only a small part in burn-in prevention, you should blackout everything, including websites (I remember firefox had plug-in like that, capable of replacing background and font colors), switch to a dim keyboard preferably without visible keys with orange-red colored font, download oled friendly icon packs, watch movies cropped in, so you're not left with permanent discoloration in place of "black bars", and play games full-screen, only then wear will be uniform. Seems like too much work. I wish micro-led displays would become widespread sooner.

I don't think factory reset or uninstalling apps will help, because it appears to be not software related.

At least not software user can update, such as display's firmware, but I don't know for sure just how independent display is from other phone's guts. Even then, I don't think firmware can fix this.

The phone is under warranty, since it's new, used for a few moths, and unmodified, but sadly is probably not an option, because in my country, gaslighting customers is fairly common. Service center will probably take it away for a few weeks, then return it scratched up, and say they didn't find any issue. So unless it's a serious burn-in, that's visible always and on every background, it'll be extremely difficult to make a return, and even then they'll probably tell it's normal wear, but then at least you can without explaining too much contact consumer protection and show them the problem.

Software used for discovery and testing:

• Super Cat Bros (video game)

https://play.google.com/store/apps/details?id=com.FDGEntertainment.SuperCatBros.gp

Play it for an hour (or more) and then test on solid darker pastel colors, do you see discoloration? Report for how long you played and how long discoloration was visible. Do not reopen game when retesting discoloration, because it may appear permanent. I know some people are not good at seeing minute differences in shades, but at first it should be very obvious which parts were black bars and part where game ran.

• Display Tester (app)

https://play.google.com/store/apps/details?id=com.gombosdev.displaytester

Very good display tester, free, lots of features and tests, and works on wide-screen displays, enable "use immersive mode if possible" in the settings. I think default color in BurnIn tester is very good at revealing discoloration, but you can play with sliders, just remember position which reveals discoloration the best.

• I'll also attach solid color image, which works for revealing discoloration.

And another dark gray image, which also helps reveal discoloration, use in dark room at around 50% screen brightness (play around), no matter how much you zoom in or out, it appears like screen has gradient, notifications bar icons are also visible, not sure if it's temporary or a permanent discoloration. I recommend opening these images with a gallery app, set to full screen, or simply pinch to zoom, and tap screen one time to hide gallery's UI elements. Tilt phone left and right, move towards and away from yourself, do you see discoloration?

You can also open them up with browser, and examine your screen, but I found you can't hide all UI elements, so better use gallery or other image viewer.