I don't know if it's because of the xbox game bar when I'm invited to an invite-only world, but my mouse cursor goes out of Minecraft while I'm playing the game.
After that, the mouse cursor will be out of the game even if you open the world or the world displayed in the friend field.
Restarting Minecraft does not fix it, restarting your PC will fix your world and the world in the friends section, but the same thing will happen again if you are invited to an invite-only world

There may be some weird things because I use translations