It’s not, it’s a relay attack. Someone stands near your keys with a receiver, and they relay the signal to a transmitter near the car. It works because it’s the actual signal from your keys.
Never keep your keys near your door, unless they’re in an RF shielded holder.
The “mimic” you’re talking about is called a replay attack, and those have been prevented for a long time with rolling codes.
It’s not, it’s a relay attack. Someone stands near your keys with a receiver, and they relay the signal to a transmitter near the car. It works because it’s the actual signal from your keys.
Never keep your keys near your door, unless they’re in an RF shielded holder.