Even though the field is not validated (and not green), I get to move on from the payment windows, and a succesful subscription - I wonder if this is a case that can only happen with these test payments - but shouldn't an invalied field stop the form from being submitted in the first place?
It should be possible to move from payment element to payment element but not to submit the payment form if there are any invalid payment values, so there is a bug, yes.
Even though the field is not validated (and not green), I get to move on from the payment windows, and a succesful subscription - I wonder if this is a case that can only happen with these test payments - but shouldn't an invalied field stop the form from being submitted in the first place?