Most offers are fine, the A100 I rented was a scam, however. A scam in terms of: advertised as A100, performing like a 1080. I guess the seller partitioned the card or rigged the id. You can report frauds like this on their page but only while you are renting.
I would hope vast.ai would be able to detect MIG at least.
It could also be a low power cap - I had a Dell C4140 for a bit with 220V power supplies and 120V power, locking the entire thing to ~50% of the max power cap per GPU basically.
