Yes, I understand that in the long term it is not scalable for the
plocate maintainers to add every possible exception due to some software
writing large amounts of files in a given location and I think it is
fine to close this bug.
In the long term, however, maybe something like what it was suggested in
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1012619 might work.
The plocate maintainers don't need to add all the possible exceptions,
but rather, each software that is aware of plocate would add a file
under /etc/updatedb.conf.d that plocate would then concatenate. In this
case, incus installation would place a /etc/updatedb.conf.d/incus.conf
that adds /var/lib/incus/ to PRUNEPATHS.
Thank you!