ప్రత్యుత్తరాలన్నీ (1)
Mozilla only provides internal Firefox updates (with .mar files) to their official tarball builds from mozilla.org like say https://www.mozilla.org/firefox/all/#product-desktop-release and no internal updates to any package/snap builds.
You appear to be using a package build of Firefox from Ubuntu so you will need to check for Firefox updates in your package repository manager.