Question about UDP_ONLY mode with gfwlist.acl

[AaronChen0]

trafficstars

Hi, I have the following scenario of using sslocal. Related to https://github.com/shadowsocks/shadowsocks-android/issues/3070. Having 2 sslocal instance with the same config, the only difference is that one is tcp_only and the other one is udp_only.

sslocal -b "127.0.0.1:1080" -s "1.1.1.1:12345" -m "aes-256-gcm" -k "hello-kitty" --acl acl.txt
sslocal -u -b "127.0.0.1:1080" -s "1.1.1.1:12345" -m "aes-256-gcm" -k "hello-kitty" --acl acl.txt

With a proxy-all acl, the remote server can receive both tcp traffic and quic/udp traffic. But with a gfwlist acl, only tcp traffic is received, no quic/udp traffic. Tested with visiting youtube for quic/udp traffic. Why?