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+W... - https://dshield.org/forums/diary/More+DNS+over+HTTPS+Become+One+With+the+Pac...
Thanks, and best regards, Peter Müller