If you enter a world in the settings Cheatsauf and open it in lan you can allow cheats there no matter if the difficulty is on simple or hardcore.
Related issues
Comments
[Mod] markderickson
MC-204906
Game mode can be changed although you have cheats off
Resolved
Duplicate
0
[Mod] markderickson
migrated
(Unassigned)
Unconfirmed
(Unassigned)
20w45a
Retrieved
Hello! This looks to be a duplicate of MC-134, which has been marked as being intentional. You can feedback about this resolution here, if you'd like: http://feedback.minecraft.net/