So I have seen this for awhile and had not mentioned something before partially because its not a game stopper and so many things are going on with piefed dev I hated to bother. I kinda expected other people would be seeing it and it would likely get attention and maybe it has but I just have not seen it. Anyway I attached a screenshot showing how the dropdown menus get obscured by the site and its not just obscured because the site under the dropdown seems to have interaction priority. The funny thing is when I click on images and get the larger version like sometimes something like this happens and at other times the pop up image will correctly be in front of everything. Im not sure if its the type of image or what but the effect does not always happen with pop up image. It basically always happens with the drop downs though. I changed to default theme and some other themes and this issue consistantly happens.
I have a similar-ish problem, but on qutebrowser. If I interact, I get a similar text overlay of a piefed homepage, so i have to reload the page and then it does not happen. problem is that i can not reliably recreate it, with each page it is pretty much 70-30 odds of happening vs not happening. never got it in librewolf (firefox). thought it was a caching related issue, so cleared all of site data, also cleared all qutebrowser data once too. relevant things in config are dark mode, and a css to make backround black and text white (i can share it, just do not think it is very relevant because i have seen it happen without that css)