Unbound SERVFAIL - Local Domain is added to external requests

[Firewire]

Hello,

my OPNsense is configured as a DNS upstream server and the domain "home.arpa" was added in General System Settings.

I have an issue where the domain is applied external requests.
When DNS requests are answered by Unbound, the "home.arpa" domain is added as a suffix.

Example:
cloud-jobs.linkplay.com
is changed to
cloud-jobs.linkplay.com.home.arpa

That happens not with all, but with many domains and results in a SERVFAIL error.
Unbound is set in transparent mode, to resolve local requests (for DHCP static leases) and external requests

Could someone tell me how this can be fixed?

[Patrick M. Hausen]

Are you sure it is not the resolver library on the client doing that? That's how it's supposed to work.

[Firewire]

It seems like that indeed, since only a few specific clients are behaving like this.
Doesn't seem to be a problem at all, since I discovered no issues so far on my clients.