@DonC is exactly right. This is an obvious feature that is logical and necessary.
If the system is disarmed…
Having it detect you or your family’s motion adds no good security benefit, wastes the battery, and creates too many unnecessary events.
It really depends on where you put the motion sensor. If you are like most families, in a main area is most-likely where it’s going.
If you have it setup in a garage or some room that doesn’t get many motion events, it might make sense to want to know about all motion in that area.
This needs to be a feature within the app - disable motion detection when system set to “Disarmed”.