Items after death - problem (1.16.5)

I have a problem on my server ... when I connect, everything works and there wasn't any problem. Recently, however, my friends told me that after death the inventory remains ... I tried /gamerule keepInventory false, it will write a message that the rules have changed, but items still remain in the inventory. I don't know what to do with it. Any advices?

I know that. I want the inventory to be clear after death, but even if I write this command, items still remain in the inventory and I don't want that. I want items from inventory to normally fall to the ground after I die.

Items in inventory still here...

Yes...

Builder, Carz, Essentials, EternalLight, MultiWorld, PowerRank, SkinsRestore, SuperChair, TreeAssis,

WorldEdit, WorldGuard