Re: downgrade ghostscript to get convert etc working

[Marco Möller]

If the newer version (currently v9.50 in bullseye (testing)) would solve 
the problem, then you may want to ask if someone could place this newer 
version from bullseye into the buster-backports repository. Afterwards 
you could install the backported version 9.50 from there without hassle. 
This would be the Debian way to follow first. Only if not succeeding 
this way, then think about tinkering.

More information on this concept can be found here:
https://backports.debian.org/
The corresponding mailing list is this one:
https://lists.debian.org/debian-backports/
Good luck! Marco.