doveadm expunge not expunging anymore

Hello,

I have migrated my mailbox server from Dovecot 2.1.7 (Debian 7) to Dovecot 2.3.4 (Debian 10) and have a crontab setup in root to daily delete all mails in the INBOX of a specific user which are older than 90 days like this:

/usr/bin/doveadm expunge -u username\@domain.com mailbox INBOX savedbefore 90d

Unfortunately this does not work anymore. I also tried to run the command manually as root which does not return any output or errors.

Any idea why this command does not work anymore?

Regards, Mabi