as @MoritzMuehlenhoff found when running an audit script, @Volker_E's shell user "volkere" does not match the LDAP user, which is "volker-e". Back when i created it in T143465 i wanted to avoid the literal "-" character in shell user names and stick to [a-z] without a literal "-", but it is indeed a legal character and these usernames should match per policy.
rename the shell user to match the LDAP user