If you want a potion coat to be blacklisted (no longer be able to be coated), then put its .json file in this blacklist folder.

In Minecraft, there is a bug with the harming effect that lets it do more damage with weaker hits. In the base game, this bug affects harming tipped arrows. 
The bug also affects this datapack, which is why harming and strong_harming are blacklisted by default. Drag them out of this folder and into the item_modifier 
folder if you want them to no longer be blacklisted.