DrayTek support said this is 'normal' and didn't give an explanation what the message actually means.

I have done some more digging, it seems Apple is doing a type 65 request, if this fails it does a regular DNS lookup, so I suspect that the first 'type 65' request is what Draytek is complaining about:

https://developer.apple.com/forums/thread/663440

and for those that want to dig even deeper:

https://datatracker.ietf.org/doc/draft-ietf-dnsop-svcb-https/00/?include_text=1