When trying to join a realm, I get stuck on the "Connecting to the realm" screen before having the "Disconnected" message. I get this error in the logs:

[18:38:44] [Netty Epoll Client IO #0/WARN]: Unexpected exception in the selector loop.
io.netty.channel.unix.Errors$NativeIoException: epoll_wait(..) failed: Function not implemented 

This seems to be a Linux issue with the Netty library that was fixed in version 4.1.77.Final, but Minecraft 1.19 uses version 4.1.76.Final (see https://github.com/netty/netty/issues/12343 for more information)

EDIT: it seems to be preventing the connection to ANY multiplayer server. Updated the title.

EDIT2: For the people who want a temporary fix, I have attached an updated package manifest that downloads the latest Netty version from Maven Central.