It's fucked-up that Firefox even checks for updates itself (instead of letting the package manager do it) in the first place. It wouldn't have the bug if it didn't have the unnecessary functionality.
In context, my comment was really more about dunking on Windows for not having proper package management. Firefox only "needs" that feature because it's working around Windows' deficiencies.
I'm pretty sure it's disabled on the M$ Store version.
Also, on macOS it's so annoying that literally every app checks for (and even wants to install) updates while I have the Brew package manager installed.
Yeah, probably easiest & best to uninstall and reinstall with a package manager. Anything that manages updates will likely have Firefox configured to not check for updates
If you are a GUI kind of guy try your OS's app store.
Otherwise apt, yum, homebrew or winget should do the trick :)