There is the possibilty that Tesla gets VIN numbers from the US govt - and they use them up until they need more. That would make the transition from 2019 to 2020 pretty random.
I have no idea of what they use on cars sent overseas.
What we need is definitive proof that new cars for N. America are being made at Fremont. Speculating on VIN's and MY, etc. - is just speculation. If Tesla can make 5000+ cars a week in Fremont, then there will be cars showing up all over at once. Not just a few here and there.