Same thing happed to me $22.00 charges because the stated package weight was 0.5 lb and actual weight was 0.31 lb.
Tried to deal with this via chat and was told by Raziel that a copy of the chat would be sent to me but instead I received an email saying “We’ve identified that your shop may have received one or more unexpected USPS shipping label adjustments on July 4. Our technical team is reviewing this issue, and we will follow up with more information as it becomes available”.
I would like the email copy of the chat like I was told!