When you hit the F3 key on the title screen it opens the F3 Debug Menu (Can also open Pie Chart with F3 + 1), it seems that this bug only occurs in version 1.21.9 and in the newest snapshot (1.21.10rc-1). You can also open the Debug Menu Editor (F3 + F5) on the title screen but it may be an intended feature.
I am playing Minecraft on MacOS, maybe the bug doesn't affect Windows and Linux devices
Hi!
Thank you for your report!
We're already resolved this issue at MC-300118, so I will resolve and link this ticket as a Duplicate.
I suggest also to browse through the main issue for potential fixes.
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