No additional section included when resolving resolver.arpa

[Bruno Blanes via Unbound-users]

As per RFC 9462, Unbound should include in the additional section, both the A 
and AAAA records for the name of the Designated Resolver when responding to 
queries for "resolver.arpa". However, I couldn't get this to work on my server. 
I have created a local zone file for the domain and it is replying properly to 
the SVCB queries, except for the additional section. Has anyone encountered 
this issue?