A few years ago, I filed a Feedback Assistant bug report regarding an issue I was experiencing in Final Cut. In response, I was contacted by Final Cut developers who worked with me to replicate the issue and then shipped a fix.
Just one anecdote, but some reports definitely get looked at.
I had the same happen for a bug that would toggle off "Do not create a new Apple Ad Identifier Code" (or whatever it was called). It meant that even if you explicitly opted out of Apple's Ad tracking, you would get opted back in with almost every iOS update.
I assume this would have landed them in hot waters with EU privacy regulators, so they were very keen to replicate the bug and then have me check if it no longer happened.
On the other hand, the "first screenshot fails to display screenshot preview and doesn't flash the screen" has been in iOS for 3 versions now. I've reported it thrice, and no one has given the tickets a second look, marked it DUPLICATE, or anything. And every time I mention it, at least 3-4 other people comment on also experiencing the bug, so I assume Apple must be pretty aware.
Just one anecdote, but some reports definitely get looked at.