I managed to reproduce this on accident on 1.16.5, though I didn't cancel the joining, I just joined mineclub while opening my minecraft server on localhost and managed to join both servers at once, actionbars and chat were updated at real time from the other server and this kept on even after relogging from my minecraft server, and I couldn't join mineclub because it said I was already there.
[media]
It was constantly flickering between mine and their actionbar and mine and their time on the minecraft world, so it was going night and day constantly and I managed to join with their server texture;
So basically I'd get a very weird buggy relay from their minecraft server.
Vinícius Vieira Cavalheiro
I managed to reproduce this on accident on 1.16.5, though I didn't cancel the joining, I just joined mineclub while opening my minecraft server on localhost and managed to join both servers at once, actionbars and chat were updated at real time from the other server and this kept on even after relogging from my minecraft server, and I couldn't join mineclub because it said I was already there.
[media]It was constantly flickering between mine and their actionbar and mine and their time on the minecraft world, so it was going night and day constantly and I managed to join with their server texture;
So basically I'd get a very weird buggy relay from their minecraft server.