I've enabled both sql and oauth2 passdb,
regardless of the method used by the client, I get the following error:
Jan 1 15:38:56 mail dovecot[52828]: auth: Panic: file http-client.c: line 646 (http_client_context_close): assertion failed: (cctx->clients_list == NULL)
Jan 1 15:38:56 mail dovecot[52826]: master: Error: service(auth): command startup failed, throttling for 2.000 secs
Jan 1 15:38:56 mail dovecot[52828]: auth: Fatal: master: service(auth): child 52840 killed with signal 6 (core dumped)
Jan 1 15:38:56 mail dovecot[52828]: imap-login: Disconnected: Auth process broken (disconnected before auth was ready, waited 0 secs): user=<>, rip=192.168.1.104, lip=192.168.1.101, TLS, session=<QW7rFYfUgcTAqAFo>
If I remove the oauth2 passdb, there are no problems.