I'm on Debian testing with package printer-driver-cups-pdf version 3.0.1-14.
I get broken output file names as well, and I think it is an upstream bug.
Here is my configuration as dumped by cups-pdf:
-- snip --
Thu Mar 9 14:50:11 2023
Package: printer-driver-cups-pdf
Version: 3.0.1-5
Severity: normal
Dear Maintainer,
using the cups-pdf printer with a short document title (< 32 chars) results in
faulty generated filename. This don't affect titles >= 32 chars.
example:
lp -d PDF -t short INPUT.pdf
result:
a generated PDF
