Issue Emails to postmaster@ not delivered without root@ (custom `adminAliases`)

[jnthn]

Server operating system version

AlmaLinux 10.1

Plesk version and microupdate number

18.0.77

Per the guide, I tried updating the mail aliases to only have postmaster@ enabled:

[mail]
adminAliases = postmaster

However, when I then try to send an email to postmaster@ on some domain, the email doesn't get delivered to the administrator's address, and I see the following errors in the Postfix logs:

cannot chdir to mailname dir root: No such file or directory
Unknown user: root@[hostname.com]

After some debugging, it appears everything works when adding root@ as mail alias:

[mail]
adminAliases = postmaster root

Is it intended behaviour (that root@ is required for other aliases to function)? If yes, it may be good to mention this in the guide. If not, maybe this bug could be resolved?