From now on, the fall damage is the same on the entire server and on all worlds.
In Minecraft.
Do you mean in Fortnite?
No in Minecraft sry
This can be due to a bug, do you play in beta?
Beta? The server runs on 1.8.8
Then restart the server, otherwise contact support
What support?
What is this server? Where is it
It may be that you have issued the fall damage in your server console. Just check if that's over there.