Both the EVSE and the cars monitoring equipment will have accuracy range, plus and minus. The EVSE is telling you what’s passing through it. Is the car telling you what’s coming in through the port or what’s going into the battery. I would thing the later. That discrepancy is what the car is using for internal electronics doing there thing.

I had DMV screw up my registration. Bought it out of lease and stop getting renewals. I guess they got the release from Ford Credit after the bank sent the paperwork. I submitted praiseworthy every year per DMV and they still never fixed it. So every year I sent into AAA to pay my registration. No paper to mail on payment and couldn’t renew online.