Android phone screen - Colours when drag finger across.

[SyncroScales]

Hello,

Linux Mint xfce 20.2.

I am not sure if I can get answers on this forum, but I was wondering about Android phones.

I have an Galaxy A51. When I rub my finger across the screen, it leaves a coloured mark. It might be darker if I press hard, or not. I have noticed that it went away when I did updates. But I cannot get rid of it and it came back. I looked in the colour settings and prefrences, etc. Display, Wallpaper and style, etc. I even hard-reset it. It was weird, the system updates stayed on, even with the cache erased. I think I have read that once the Android hardware or software updates those files, it doesn't revert back.

Am I missing anything? When I do searches and search YouTube, they talk about screen refresh rate, changing themes, etc. I do not know what to call this.

It is a used phone. I thought this is supicious. Should I be concerned or is there something I can do about this?

Thanks.

[Midnight True]

i think this might be an lcd issue, i would recommend to back up your android files just in case. Best of luck