Theory: Is the car bound to a phone or an account? It would make sense for it to be the latter. In that case the VIN qr details should be stored in the account already hence no VIN qr presented on screen as it exists already.
Does that sound feasible?
Now the thinking out loud bit
if so why does the account not communicate with the car and handshake vin details on the server to allow app functions to work on your new phone. It should allow 2 users to access the same account with only 1 allowed active log in at any time I believe. The new login should logout the other one signed in.
So on the assumption you logged out on previous phone and deleted the app the account should in theory be able to connect you to the car on the new phone and still have a spare login. But how does the MG server know the old device is discontinued or does it matter?
Sorry if this thinking out loud doesn't help but for future reference, as I will be replacing my phone shortly, it does need us to understand how it functions after phone transfer going forward. You are the guinea pig unfortunately!
I am told that second hand cars needed to be unbound by the previous owners or MG needs to do the reset for the next owner.
Alan