I just got their new 3d printer and was having a great time with it... Won't be updating firmware or buying anymore products with them until they fix this
According to the bambulab blog (on the official bambulab website) they explicitly state that you are free to downgrade or not upgrade and your printer will still work.
Edit: they even have a specific note about users that never want to upgrade and it states that it is fine, and their printers will still function.