not working anymore: @domain as a wild-card for relay_recipient_maps

Hi,
an urgent problem here:
I updated a mail server and after that postfix rejects emails for which the server is a relay.
The concerned domains are listed under "Advanced Email Routing" for the server rejecting the email.
Under "Relay recipients" is one entry for each concerned domain: "@domain" as wildcard.
Worked fine until today. From now we need to list any possible email-address under "Relay recipients".
Any idea, why?

Regards
cmks

 

Debian GNU/Linux 10 (buster) / ISPconfig 3

 

https://www.postfix.org/postconf.5.html#relay_recipient_maps