Can confirm this bug can happen, especially when alt-tabbing.
This can easily be fixed by pressing esc again ingame or by what @Rayth did with restarting their pc.
Cannot confirm
[media]Cannot reproduce the bug.
This issue may be due to your resource packs if you have any enabled.
Pink Glitch is back in v1.19.73
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However, when rejoining, it seemed to fix itself and back to it's current state. Nonetheless, it still happenened and isn't fully resolved.
I've had this bug, but this still allows friends to join, even with the custom name.