Hello Stefan, hello *,

for detecting DNS over HTTPS traffic without interfering with the connection, perhaps
these articles might be helpful:
- https://dshield.org/forums/diary/Is+it+Possible+to+Identify+DNS+over+HTTPs+Without+Decrypting+TLS/25616
- https://dshield.org/forums/diary/More+DNS+over+HTTPS+Become+One+With+the+Packet+Be+the+Query+See+the+Query/25628

Thanks, and best regards,
Peter Müller