I'm not sure if this messaging change from fsdbeta as of late June indicates an actual change or increased vagueness…
To transfer: If you have sold or traded your FSD Beta feature enabled vehicle and have purchased another, please provide us with the old VIN number to opt-out and request access on your new vehicle via “Request Full Self-Driving Beta” button.
For reference, the response as recently as mid-June used to be:
If you have sold or traded in your FSD Beta feature enabled vehicle and have purchased another, please note that it is not transferable to your new vehicle. You can request access on your new vehicle via the “Request Full Self-Driving Beta” button.
One interpretation is that you can actually transfer with fsdbeta team doing something special for your old and new VIN. Another interpretation is that you can "transfer" by doing the same safety score and opt-in steps and you might get FSD Beta again.
At least the new version of the message clearly includes the requirement of "At least 100 miles driven on Autosteer."