Biomes and Dimensions Bug

You attached .jar file and not exported shareable zip file so I can't really help there.

Please provided things needed, read the rules again and leave a comment when you do so..

The Mcreator server is not crashing the other server localhost or Server hosters crash with this mod , Bioms and Dimensions is the ERROR!

Could you explain what you wanted to tell here?

Also it seems you use plugins again, with cooperation like this we will come nowhere, you see?

I see your problem. This code:

public void clickSync(PlayerInteractEvent.EntityInteract event) {
        event.getPlayer().getPersistentData().putDouble("fuel", event.getTarget().getPersistentData().getDouble("fuel"));
        event.getPlayer().getPersistentData().putInt("connectedfueledentityid", event.getTarget().getEntityId());
    }
    @SubscribeEvent
    public void playerTraceCheckSync(TickEvent.PlayerTickEvent event) {
        PlayerEntity playerEntity = event.player;
        Entity entity = playerEntity.world.getEntityByID(playerEntity.getPersistentData().getInt("connectedfueledentityid"));
        if (entity != null) {
            playerEntity.getPersistentData().putDouble("fuel", entity.getPersistentData().getDouble("fuel"));
        }
    }

is a dirty hack that will work on single-player or LAN but ultimately fail on dedicated servers. If you want to sync data, you will need to implement packets.

Or simply use PLAYER variables.

Another part is still caused by MCreator, but I am still investigating it

this custom code is working i have tested and in the old snapchot is this code working

This code will not work properly on a dedicated server. No other way around, do you understand network communication and how packets work in MC?

I managed to find the cause with MC, this will be fixed in 2020.4.