The new gamerule (/gamerule reducedDebugInfo) that allows you to remove coordinates from the debug screen can't be changed unless you have cheats enabled. There should really be an option to turn this on when creating the world or it should be automatically turned on if in hard difficulty.
MC-65763
Debug screen can't be limited without enabling cheats
Resolved
Invalid
0
you can turn it off on multiplayer settings (just client side). This is a gamerule and it need to use cheats do disable in the world