Currently, Fake Players appear in rankings. It's actually quite interesting to know stats about them, however, this does cause some issues.

They easily occupy top slots as every player uses the same FakePlayer. As such they take up 1st/2nd/3rd place bonuses.
They are unable to accept bonus drops. Causing lots of item entities in the world that will never get picked up.

They also result in some rather unfortunate dupe bugs: https://gfycat.com/DishonestConcreteArcticduck

As such I believe Fake players should not have access to skills.

forge-31.1.0
Zmod 1.15.2-1.04.jar

From what it looks like you are using the Block break event to run things. This event can get canceled resulting in the block not being harvested.

Additionally, I've been told this will become the proper way to add additional drops at some point MinecraftForge/MinecraftForge#6401

So its using a simple mechanism of capabilty which are joined to the players when they are joined on server. I didnt consider any fakeplayers etc. So i dont know how your mod working. there will be always compability problems with others mods. Maybe in the future i will look at that.

Other than the issue that the block break event is not at all meant for dropping extra stuff, the simplest "patch" for this would just check if (player instanceof FakePlayer) then don't add the capability. Still would not be ideal given the event you are using is not meant for spawning additional drops or the like as it can be cancelled... but would stop it causing strange interactions with fake players at least.

In next patch i will fix it. Currently i dont have time for this :)