Firefox from Mozilla APT repo keeps asking to be set as default and creates strange .desktop file

[szx]

I installed Firefox on my Ubuntu 22.04 from the Mozilla APT repo as suggested here:

https://support.mozilla.org/en-US/kb/install-firefox-linux#w_install-firefox-deb-package-for-debian-...

It works fine, however, the problem is that when I launch Firefox it keeps asking me to set it as the default browser application when in fact it is already the default (I can confirm it in Settings -> Default Applications). If I answer Yes, it creates a new shortcut (.desktop file) for itself in ~/.local/share/applications for some odd reason and names it something like userapp-Firefox-XXXXXX.desktop. And after I do this, there are two instances of Firefox listed in Default Applications dropdown.

I don't understand why it can't just use the existing file /usr/share/applications/firefox.desktop. Can anyone elaborate?

[harpia]

I just hit this same problem on elementary OS 8 (based on Ubuntu LTS 24), so I've written a bug report: https://bugzilla.mozilla.org/show_bug.cgi?id=1963970