You would be horrified if you would know how much pre-‘20s or even pre-‘10s software is still running in production out there. Here we are talking about a huge enterprise and a somewhat complex migration (from tiller) but you can easily find outdated software without these aggravating circumstances as well.

Software from 2019 is horrifyingly outdated? If updates with security patches exist but haven't been applied, sure, but that's not really a default scenario depending on the stack.

I’ve only used 2020 because of the example in question. Security patches might or might not have been applied in both my imaginary example and in real world.

In my experience, "deprecated" is often taken as "we can still use that, it is not removed yet", which I find somewhat disheartening sometimes.

That's easy though, the removed part can also be ingored by mirroring package repositories for RHEL/ Debian-based systems.

You should see how much outdated / unsafe / unpatched legacy code is on Microsoft Dynamics.