This also applies for the perl version they shipped, perl releases are supported for 3 years, Debian for 5.
It's inevitable that you're going to get mismatches between OS support and "official" support for the specific packages that go into that release. Not all projects provide supported releases over a period of years, so distros just do their best to patch any issues that upstream has stopped caring about past that point.
In practice the only thing that's going to be a big worry are new security issues, which upstream is usually willing to go out of their way to fix for versions still used in the wild, even for technically "unsupported" releases, at least the Perl project is, I don't know about Python.
I'd expect most packages to be EOL from the perspective of upstream by then. It's a normal thing for distributions to backport fixes, sometimes even develop them themselves when required.
It's inevitable that you're going to get mismatches between OS support and "official" support for the specific packages that go into that release. Not all projects provide supported releases over a period of years, so distros just do their best to patch any issues that upstream has stopped caring about past that point.
In practice the only thing that's going to be a big worry are new security issues, which upstream is usually willing to go out of their way to fix for versions still used in the wild, even for technically "unsupported" releases, at least the Perl project is, I don't know about Python.