This is after some testing in a creative world because in the survival it doesnt work either. Every other tool and armor piece heals with the mana but the pickaxe doesnt. I have it SS in both worlds and it doesnt change anything.

Ive noticed it is taking mana because it updates every x tics and i cant mine something like obsidian. But it is not healing itself, so i dont know what is doing.

UPDATE

I just tabbed back and my pickaxe on the creative world (the one from the screenshot) just went back to D. I took it from the creative menu. Maybe even if the pickaxe is SS it still takes mana in and somehow got over the limit and went into the negatives. This is so strange.

Not reproducible in the latest version, what version of forge, libx and mythic botany are you using?

The modpack is 1.18.1 and forge 39.0.79. I'm going to search for the latest version that works with that and update

It works now. Im going to talk to the modpack and server admin so he changes it.
Thank you very much.