Disclaimer…My only experience is with an Android. Have you changed any settings recently??? That usually messes me up big time!!! If no…I usually do the same as @Entropy by going into landscape, minimize & then maximize which often fixes the problem. Yes, it’s a pain but better than nothing!!!You might want to do a search on your phone for “video” & see what settings you have available & what might need adjusting. I don’t take a lot of pics & I seldom if ever make a video, so my problem is mostly on youtube. If your situation is, I’m out of ideas!!!
Oops…just remembered another thing. In settings, go under “Accessibility”, then “visibility enhancements”. I think there is a “screen zoom” where you’ll find a “slide” to adjust the size of your screen. It’s been a while since I’ve had to use that, but it won’t hurt to look. Every time I have an update, my phone goes crazy & I start looking for fixes. OK…now I’m officially out of ideas so I hope it helps!!! Off to bed…niterzzz