Stripe doesn’t collect the customer name for normal checkout. It is only collected with the address field (if you enable address collection). This name value is not present at all on transactions without address field collection. So we didn’t create a tag for it.
You can get the name with the address field if you use the address merge tag. For example: {billing_address}
Maybe we can add a merge tag for “customer name” which will only work when the address field collection is enabled. Will that work for you?