SMT Mirroring fails with rpmd error

we do have troubles mirroring SLES 15 SP2 repositories on our subscription management server with SLES 12 SP4.
in the smt-mirror.log I see errors like this:
MT::Mirror::RpmMd - [error] Error getting patch data from repository: DBD::mysql::st execute failed: Data too long for column ‘DESCRIPTION’ at row 1 at /usr/lib/perl5/vendor_perl/5.18.2/SMT/ line 397.
Repositories with errors :
2020-11-12 14:22:11 main - [info] * SLE-Module-Basesystem15-SP2-Updates for sle-15-x86_64 (
Installed smt version: 3.0.42-52.38.1