For 1. Hyundai visibly warns you it slows down charging and 2. it is a load on the battery that is already stressed with charging. TeslaBjorn on YT frequently kills the A/C when DCFC if the vehicle being testing is thermal throttling. This has to be verified with a OBD port adaptor and scanner app. Scan my Tesla is very popular for Tesla’s. I really should invest in that tech, so I know exactly how much effect it actually has.