reverse performance while charging and not charging

when i play games with charging my laptop, normally it would boost my performance a lot, but idk why this time it got reversed, so i got a problem in my laptop performance in a few games and im randomly check with turn off my charger to see the result, and my fps just drastically flew high until 100's. and when got charged again, it dropped to 60 ish, like the fps got capped when charged, and not capped when not charged.