This is a Handly Mod that displays debugging info in version 1.16.50 of Minecraft.
When you join a world of your choice, a button called M will appear in the upper right corner.
Pressing it will bring up the debug information.
The debugging information displayed is:
-A version of Minecraft
-Detailed player's coordinates
-Player's block coordinates(This is the same as the default player coordinate display)
-Player's chunk coordinates
-Whether the coordinates you're standing on are slime chunks
-Seed value(This doesn't work on the server)
If you press the button again, they will be hidden.
Maybe you should turn off the default coordinate display.