dns64 in unbound broken after update

[ctr]

I recently updated to OPNsense 26.1.8_5 and afterwards my IPv6-only setup lost connectivity to the IPv4 world.
Although the DNS64 feature is enabled ("Enable DNS64 Support") queries to a A-only hostname results in empty responses. Previously I've got a synthesized AAAA record as expected.

edit: this only happens in combination with AAAA-only mode (aka "response-ip: 0.0.0.0/0 redirect")

[Monviech (Cedrik)]

https://github.com/opnsense/core/issues/10312