Note 20 Ultra flicker issues

[userJIcqjxAwyJ]

I have a brand new Note 20 Ultra with the flicker issue right from the start. I've searched everywhere for solutions but none have worked so far.

It looks like the quick flicker you get when taking a screenshot, except it starts from the top left corner rather than all around the screen and is not quite as bright. 

Appears using any app and also on the home screen

The only other thing I have noticed is that if I press the 'recents' icon the Messaging app shows - even if I haven't used Messages (including from a fresh forced reboot) but if I tap Messaging it disappears from recents but the app doesn't open.

The last resort is the full factory reset but I see no point as the issue has occurred from the first time I used the phone.

[Edit] Other people also have the same problem (https://us.community.samsung.com/t5/Note20/Note-20-latest-update-and-issues/m-p/2006513#M31467) so it would appear it's not just my new phone.

They describe the issue better than I can. I saw a video online of the "flicker" issues and my problem is not that - a "flash" is a better description.

[TheGalaxy]

Update all apps and UI
if not
Wipe cache partition.
Boot to safe mode and test
If OK: factory reset.
If not: flash with Odin.
If not: disassembly, disconnect battery, hold power button, connect and test.
If not: defective screen.
Proceed at your own risk

[Lostinmygarden · Accepted solution]

https://us.community.samsung.com/t5/Note20/Note-20-latest-update-and-issues/m-p/2018258#M31551 

[RedDragon]

If you got it brand new it is best to return it for a new device. 

[userJIcqjxAwyJ]

Good point and that was on the list. But as it appeared a Samsung update issue, it was likely that another new phone would have the same problem

The issue was solved as above - Messages app "always on top" creating some sort of conflict. Disabled "always on top" and now issue appears fixed.