In rare cases upstream APT (deb content) repos can exceed size limited DB fields
The issue was reported here: https://community.theforeman.org/t/katello-value-too-long-for-type-character-varying-255/24953/26
It is being fixed on the pulp side under this issue: https://pulp.plan.io/issues/9277
However, Katello also stores some of the affected fields in the Katello DB, with the same limit originally set by pulp_deb.
Therefor, this will also need to be fixed on the Katello side.
I expect the pulp_deb fix to make it into a pulpcore 3.15 compatible version. Due to DB migrations, it will not be possible to backport the fix any further.