There are people here that would love to have your problem. They hate start/stop.
Seriously, there are certain circumstances where the engine will continue to run. Check your Owners Manual.
Here's what the 2019 OM says:
To maintain vehicle performance, other conditions may cause the
engine to automatically restart before the brake pedal is released.
Auto Stops may not occur and/or auto restarts may occur because:
. The climate control settings require the engine to be running
to cool or heat the vehicle interior.
. The vehicle battery charge is low.
. The vehicle battery has recently been disconnected.
. Minimum vehicle speed has not been reached since the last Auto Stop.
. The accelerator pedal is pressed.
. The engine or transmission is not at the required operating temperature.
. The outside temperature is not in the required operating range.
. The vehicle is in any gear other than D (Drive).
. Tow/Haul Mode or other driver modes have been selected.
. The vehicle is on a steep hill or grade.
. The driver door has been opened or driver seat belt has been unbuckled.
. The hood has been opened.
. The Auto Stop has reached the maximum allowed time.