I’ve noticed the same thing.
Outdoor frontdoor cam set to 20 seconds end early of motion stops
Someone will leave my house and it will start when the shadow of the person is detected, so awesome. Then it ends at 7-8 seconds while they are still moving around and locking the door and clearly still in view of the camera and motion is still evident.
Today it caught the mailman leaving the front door area, got 1/2 across yard in 6 seconds and the recording stopped when he was clearly still walking sideways across yard and still working my preset time of recording.
Time to set them all to 30 seconds and NOT end clip early to see that happens