Server to Singleplayer world has issues.

So i run a java server on a computer and that computer has become too slow, so i took the world and placed it back as a normal single player world. I then optimized the world for 1.18.1. Now half the commands are missing for normal single player worlds such as gamerule... I attached the world data below. if i need to send it some other way let me know. The Server was a java server running the latest version. You also cannot access a command block... and command blocks are not able to execute their commands.