A lot of vehicles - my wife’s 2015 Kia included - have a very flawed implementation of rolling key encryption. Basically, you need to capture three consecutive keys. The receiver is programmed to allow any future key (in case the fob was pressed away from the car), and will happily reset to past keys when you send three consecutive keys in sequence.

Ostensibly this is to avoid people’s fobs from becoming “unpaired” somehow if the car receives a future key. You just hit the button a few times and it works. In practice, it’s trivially easy to exploit.