Mobs Dont Naturally Spawn in my Fabric 1.16.4 server

I have a fabric 1.16.4 server but mobs dont naturally spawn in my server.They can spawn from spawners and /summon command so my servers difficulty is not peacefull or mob spawnings are not disabled.

Quote from andreCondamine

Are you allowing spawn mobs?

İn settings

Yes as i said they can spawn from spawners and /summon command.

Yes i allowed it in the settings menu.

spawn-monsters=true

Difficuly is set to hard

Quote from Roman

Does the problem persist if you generate a new world?

I just changed my servers difficulty to peacefull then restarted the server and changed it back to hard and it somehow worked.