The OpenVPN protocol is detected and blocked. Connections not using symmetric keys or using "tls-auth" are blocked at handshake, and connections using the new "tls-crypt" option are detected and throttled (under 56kbit/s) by the QoS filtering system
Tor Obfs4 bridges still work in China as long as the IPs are discovered through social networks or self-published bridges.
Tor now primarily functions in China using Snowflake and meeks which works via front-end proxies hosted on Content Delivery Networks (CDNs) to obfuscate the information coming to and from the source and destination, it is a type of pluggable transport. Examples are Microsoft's Azure and Cloudflare.
These days, the TOR anti-censorship team seems to be putting all its faith into a pluggable transport called SnowFlake, which also tries to imitate video conferencing software.