Hello people. I came back to this forum after some months of inactivity to share my solution, and i hope it works for someone else.
This app (Oled saver) has been a saviour for my eyes. I don't experience any symptom when i'm using it. I know i said before i tried it and it didn't work, but this time i left enough time for my vision to recover and symptoms slowly began to fade away while this app was active. So if you tried it before and were expecting inmediate results, please give it a try again, at least a couple of days.
This app has disappeared from the Play Store, but you can download the APK (i think last version is 1.39). Give it all permissions and set Basic Physical Brightness to 255. And make sure it keeps running on the background at all times.
I'm using it on a Redmi Note 9S, so it doesn't matter if the screen is IPS or Amoled. This worked for me and i'm hoping it will help someone else.