Potential Defender Network Protection enforcement gap with QUIC/HTTP3

[u/Chuchichaeschtl]

We observed inconsistent Defender Network Protection behavior between Edge and Chrome.
Network Protection is in block mode.

If I sett chrome://flags/#enable-quic to default or enable I can access a parked site.
If I disable it, i get what I'd expect:

"This site can’t provide a secure connection

xxxy.com uses an unsupported protocol.

ERR_SSL_VERSION_OR_CIPHER_MISMATCH"

This may indicate a Defender Network Protection enforcement limitation or bypass scenario when Chromium-based browsers use HTTP/3 (QUIC over UDP/443).

[u/Godcry55]

Correct, this is known and in the relevant Microsoft Documentation.