Screen suddenly half black? Still responsive

%#*@! That's an amazing answer, I will try all this, I'm also doing a backup to try and do a hard-reset.

Thank you very much for your time!

The same thing happened with my phone and I noticed it would happen/get worse when I used the phone outside. It's due to the automatic screen adjustment for the light. To minimise the issue go to Settings -> Display and then turn off auto brightness. The flickering came back after a while, but not as opaque as before

I have a Galaxy S9, and almost right after I got the phone, it started having screen issues. Sometimes half on, sometimes kinda transparent black, random flickering, etc. If you've got these symptoms, then you may be in luck. I finally narrowed it down to overheating, as it would work just fine after I put it in the freezer for a few minutes. But mine just kept on getting worse, so I went crazy searching for a solution til I finally found one.

Drag down from the top of phone so you can see all the tools, like wifi, Bluetooth, etc....find the one that says "Always on display " and make sure that's checked. Then, turn the screen off.

Now, every time you want to use the phone, don't hit the power button once, instead, just double tap the screen, enter your password, and boom. Working beautifully.

Hopefully this was your problem also. If not, I'd just get a screen replacement if I were you.

This is my issue and I first fixed it by laying it on my radiator to warm it. Now though its back and that isn't working so I tried cooling the phone in a freezer but its not worked I will add that I dropped the phone and THAT worked lol but now its back and i can't fix it