Whenever I shift+hover over a tool or weapon while I have one equipped, this happens:

Original report: EnigmaticaModpacks/Enigmatica6#5241

Hmm, that is strange. I will look into this shortly, I suspect a conflicting mod.

Great work tracking it down!

Sorry for the delay, it has taken several days to narrow down the issue, but I've finally found that version 3.9+ of JustEnoughCalculation is causing this issue. The source for this version hasn't been uploaded to their Github yet, but I will try to look into this to see if it is something I can fix from my side.

Looks like this bug is affecting a bunch of other mods, I believe this issue is related: Towdium/JustEnoughCalculation#116