> It doesn't imply anything serious, just that it can be built from source and that it passed the distro's basic diligence and guidelines.
For a modern web browser it probably doesn't achieve the latter. Both Chromium and Firefox are too complex for Debian's meager backporting resources. So they make an exception to their guidelines and ship the LTS release. I suppose the userbase just hopes that bad things don't if the browser LTS upgrade happens before the OS's LTS upgrade is ready.