The following bug has been logged on the website:
Bug reference:      18389
Logged by:          Marijo Kristo
Email address:      [email protected]
PostgreSQL version: 16.2
Operating system:   Debian
Description:
Hello,
i am precreating schemas in template1 database and setting specific
privileges.
When performing "alter default privileges for role pg_database_owner ..."
the group is recognized and the default privilege is also set. No error is
thrown. 
When i create a new database the pg_database_owner role is not working
correctly. I created then the same privilege with specifying the db owner
and then the privilege works. 
Please, check this. Thank you !
Br
Marijo Kristo