I get it on my desnapified Ubuntu, but Ubuntu says firefox is up-to-date, and the "download update" button downloads firefox-135.0.1.tar.xz but there are ZERO docs on how to update my current firefox. And running the unzipped firefox executable gives me a message that it can't find my current config, so I guess that means no addons (ublock, privacy badger, container-tabs), bookmarks, or config.

I'm taking this as a good reason to wait for an official Ubuntu update, tho, if this thread is accurate, it looks like all I'll need to keep my current version running will be new root certs.

Or a new browser, unfortunately.

Probably because snaps autoupdates without user approval.