Nickname problems

I was playing on a server with a usable nickname, but later while i was playing i left the game for a bit then when i came back and tried rejoining it refused to let me join claiming my username is not invalid,does anyone know how to fix this?

If your in-game name stops being available to you it means your support ID changed. I should be able to help with this. I will private message you shortly.

Oo thank you

Why did the support ID change in the first place?

It’s a bug that happens when things go wrong. There’s probably a sneaky bug somewhere.

A few things can cause support IDs to change, including badly timed crashes, the use of cheats, and a problem authenticating Apple or Google ID at the time of re-installation.