输入指令提示Unable to create attribute: null
1.16.5
指令:/essentials:give * leather_boots 1 0 {AttributeModifiers:[{Operation:1,UUIDLeast:5,UUIDMost:5,Amount:-0.6,AttributeName:generic.movementSpeed,Name:Speed}]}

改成/minecraft:give

仍然不行

尝试转码

自行解决:
更换PaperSpigot服务端即可