Grave Data Pack All XP Back

I want to change this data pack so that you get 100% of your XP back when you loot your grave instead of just a small portion of it. I've been trying to get it to work for a bit and even tried using other data packs and plugins instead so that I don't lose XP but they all seem to have compatibility issues with the Grave data pack. If anyone could help me change this data pack to not lose any XP like I want, I would greatly appreciate it.