Comment by jeroenhd

You don't need QUIC, TLS and other encrypted channels have the same protection.

It's not hard to identify those channels and block them. A connection used to interact with websites has completely different traffic patterns compared to a user sending all of their traffic over one specific connection.

Add to that the fact that large video streaming services such as YouTube, where you may see large quantities of data being exchanged over persistent connections, are already blocked in China, and your VPN becomes quite obvious without seeing even a byte of plaintext.

Of course for common protocols like QUIC they have their own custom solution (linked in a sibling comment), but the point is that even with encrypted SNI you will need dedicated anti-GFW protocols to stand a chance against censorship. No protocol that works well for most consumers is going to protect against the analysis a dedicated firewall with decent funding can come up with.