[NiLuJe]

For a bit of context, almost *every* distro has been packaging calibre in a subtly to overtly broken way (and usually also based on an hilariously outdated version, as @DNSB just showed), which is why it's *always* been considered an unsupported configuration. Might work well enough, or it might not. In any case, as soon as you start asking for support, the first answer will *always* be: come back after trying the actually supported setup (i.e., the upstream binary install).

The Python 2 EoL just made everything "worse" in that respect, but it's not a new thing.

If you want your distro's package to behave properly (or at least better), complain to its package maintainer. And point him/her to the Arch package, which is the gold standard for a downstream calibre package.

(Which won't change the fact that running Calibre under Python 3 is currently still considered experimental).