me neither but everyone here is saying the cart saves the information somehow.
Actually, it's one person saying it. Nintendo can track cart activity if your system is online, which is why you can't earn gold coins from the same cart on multiple systems. If you take a cart to a Switch that hasn't patched the game and this system is offline, I would be shocked if the cart is unusable. If the system is online, then yes, the servers can likely infer that it had been used to received a patch in the past.