does not work in the original launcher

[MinikPandaaaPro]

It doesn't appear in the F3 menu, nor do the servers detect it. Nothing random is happening, and it's not like custom launchers. I won't give an example name. Can you solve the problem or is there anyone who can help me? Fabric 1.21.3 Arch Linux

[MrKinau]

It's not intended to change anything visually in the game. The only thing it changes is the brand which the client sends to the server using a custom payload packet.

[mineglitch11-debug]

same issue Idk how to even use