Yeah, I wondered the same thing. It seems to be so. I don't think Apple ever states when an OS ends. It just stops getting updates. Safari 16 came out for newer OSes and Catalina was skipped. I imagine if there is some dangerous vulnerability between now and November, perhaps there could be one final security update.
Around here, "unsupported" normally refers to a device that is too old to run a specific version of macOS.
Back to the OS itself:
When Apple releases a new version of macOS, the old one receives (security) updates for about 2 years (at least that's what history taught us).
In the case of Catalina, with the soon to-be-released macOS Ventura, Catalina is expected to not receive updates anymore.
Or in other words, soon it will be like this:
Ventura: current version of macOS
Monterey: still 2 years of updates
Big Sur: still 1 year of updates
Catalina: end of updates
For the first time, maybe this is not such a big deal as Apple recently introduced XProtect Remediator for malware detection which should receive updates independently of the OS version.
Apple has made notable updates to macOS malware tools over the course of the last six months, according to updates tracked by Howard Oakley at Eclectic Lighting Company (via Ars Technica). "In the last six months, macOS malware protection has changed more than it did over the previous seven...