Today's latest pre-release has to do with some changes to chat messages and fixes regarding the state of the messages on whether they are secure or not.
Technical Changes in 1.19.1 Pre-Release 4
- Custom servers can hide player chat messages from display via a new network packet
- This does not delete player chat messages from chat logs
- Insecure chat messages logged in the server are prefixed with a [Not Secure] tag
- The order of chat messages is now cryptographically verified
- This will be used for validating the context of chat messages for Player Reports