Screen randomly turns off

I've had my phone for about 3 years now and haven't had any problems with it until now. Today, while watching a video on YT, my screen turned off, and after a long while it turned back on, and the cycle continues. It's not the phone itself, it's the screen. Interestingly, the phone still responded to touch, because I could stop a video, etc.

The phone was never dropped, water-damaged or overheated, also never been in a service center, cause I never had any issues with it.

I tried to turn it off completely, but when I turned it on, still nothing. Only after some time the screen did turn back on. Also, I tried the same with booting it into bios, but still didn't work.

Does anyone have any advice on what to do with it before I take it to the service center?