Someone correct me if I'm wrong, but I believe Software Ver 9 only went up to Ver 9.1 or 9.2 before Tesla Launched Ver 10 in Sept 2019.
Whether or not Tesla is using the official OS updates as a guideline for FSD beta. ie FSD beta 8.3 corresponded to public build ver 8.3.
Today's public build is still on 10.2.
I can see by Oct, the FSD beta would be on Ver 10. Then Dec-Feb 2021 Ver 11.