On reflection, it’s also quite possible this is a platform-specific bug. I’m on Linux. I think I experienced it in Windows a few years back, but the memory is fuzzy.
… hmm, apparently if I start a blank Firefox profile this doesn’t happen either. Though I know I’ve encountered this with at least two completely distinct Firefox profiles over the years. This bears closer investigation.
Anyway, it’s still indicative of the disrepair of this feature set. It’s still used widely enough that I don’t think it’ll be torn out, but honestly on technical robustness grounds it could warrant being removed.
But I do share your frustration: the modern web seems unusable, unless you have a collection of extensions that block ads, annoying consent forms and the likes. But once you have these extensions installed, you basically lose all support.
Sometimes stuff breaks, and it works in a new profile even with the same extensions installed... and then what? You're supposed to throw away your profile with bookmarks, CAs, years of history etc.?
Its gotten to the point where I have multiple browsers as fallback. FF with lots of essential extensions > Brave with just a few > Unextended Chromium. A necessarily ridiculous state of affairs, but there you have it.