I'm not an expert on the TLS 1.3 but the 0-RTT feature seemed like it wasn't implemented by a lot of clients so the new QUIC protocol used in HTTP/3 seems to be the workaround for that. The following recent comment and the first video linked actually had some great related info that I was recently reviewing on that topic: https://news.ycombinator.com/item?id=32572825

I don't know if the MySQL protocol itself though be able to utilize the TCP-based TLS 0-RTT functionality or not however so connecting via a regular client may still end up with a lot of the back and forth handshaking.

The newer serverless driver for JavaScript has some opportunities to take advantage of QUIC within HTTP/3 in the future as Matt mentioned over here recently: https://news.ycombinator.com/item?id=32513043

So that will be interesting to continue seeing how it evolves/improves over time.