I believe Firefox now points to its snap variant, which I discovered when it broke a bunch of my browser extensions. Switching to the official Mozilla PPA was easily enough, but left a bad taste; if Canonical continues down the route of silently nudging users onto snap, I’ll probably switch to Debian.

(I have no particular opinions about snap itself, other than that it seems poorly documented and doesn’t adhere to the “do what I say” philosophy when it’s secretly injected into apt.)