I have had that problem in general with iOS 15. Sometimes a tap repeatedly won’t register in a certain portion of the screen.
Edit: also in case anyone from Apple is reading this, I’m also constantly accidentally switching to the tab overview screen when I attempt to scroll down, which is a new annoying gesture I never ran into before and now wish I could disable.
Edit 2: my typing is also less accurate now too. I don’t have any hard evidence here, but anecdotally I am CONSTANTLY typing “abd” now instead of “and,” which makes no sense at all, given autocorrect.
Another problems with iOS 15: some videos are entirely black while playing. I looked into this and turned off a GPU acceleration option, but that only fixed about 60% of videos.