KM
From
https://www.makeuseof.com/tag/dealing-with-system-problems-in-android-safe-mode-factory-reset-and-restoring-backups/
"Most operating systems have something called a “safe mode” that lets you boot up the system without running any third-party software. In other words, only the software that is native to the system (basically, from a fresh install) will run. Windows has it. Android has it, too." --> so in Safe Mode only third party apps get out of play; the stock apps are as from last update --> since I doubt it was a third party app that caused the problem, Safe Mode does not help at all. Indeed I found no relief for my eyestrain.
"Basically, the factory reset just returns the state of your phone back to what it was the moment it left its original factory. You can see why it’s such a useful feature–especially since you can factory reset even when your phone won’t boot up normally." --> This is interesting and promising. It looks like a factory reset should return the system to when I bought the toy.
As a preliminary test, on my new phone which I anyhow want to re-sell, I updated all the stock apps before a factory reset, except Android System WebView (not sure why I did not update everything). When I rebooted the phone, all the stock apps appeared outdated.
If factory reset works, I should be able to go back to ancient times but I won't have the last version of the OS which worked fine with me. Either the first or the last. Maybe I will see what Samsung says before proceeding.
