If you join a server and cancel the connection to it while it says "Connecting to server" and then immediately joining a different server puts you into a limbo state, where you receive chat, from both servers, you can only move in one and send chat messages in one Server.
These are only examples of things that you receive from both Servers there is plenty more.
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Asteraoth
Thank you for your report!
We're tracking this issue in MC-74984, so this ticket is being resolved and linked as a duplicate.
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