Experiencing unusual USPS label price adjustments?

I didn’t even know this was a thing. I usually never check my billing but I know I just paid $200 (the threshold for my shipping labels) literally July 2nd, that’s what made me go why am I being billed again when I haven’t really mailed much since then except for the few packages on July 4th, only to find out adjustment charges of $22 each for 4 oz packages. Unbelievable!! They have to refund us our money back.