Bug maximizer doesn't take Skill MP Cost Modifiers into account.

If you have less than the "normal" amount of MP required to cast a skill that the maximizer is recommending, it will restore MP then cast the skill.

Today I have the Arcane in the Brain effect and I have the Pocket Square of Loathing equipped for a total of -6 MP. Tried getting the maximizer to cast Quiet Desperation but as I had 9 MP at the time, it used a free rest to restore over 100 MP even though the cast was only going to cost 4 MP.

Should be trivial to reproduce as there's lots of Skill MP Cost Modifiers in the game these days.

I haven't tested if it fails the other way. As in you have something like the merkin tailpieces or Amulet of Yendor equipped which increase MP costs and then try to have it cast a spell when you have enough MP to cast it normally.