Samsung S9 started to have screen problems a few weeks ago, after doing several official updates. this happened just before the 2 year guarantee expired (coincidence?). because of the pandemic I couldnt go to the samsung store and action on the guarantee. have factory reset, and clean up cache and still a problem.
does anyone have a solution or faced the same problem?
since you're with the troubelshooting tests
please contact your Samsung Support to discuss the repair options
Same issue with my Galaxy S9+. Thought it might be software, because sometime the screen will unlock and look ok, then after a few seconds, it goes back to the washed out color mode. I played with all the settings, went as far as performing a factory reset, and it didn't help.
You can play with the brightness controls and when really low, it looks ok, then 1/4 way up is the worst, where it is yellowish and dark with visible horizontal lines, like every 3rd pixel row has no color. When you max the brightness it becomes usable, but the color is still not right, and really not a useful work around, (battery, eye strain etc.)
Maybe something is loose inside the phone?