Normally you should not feel a downshift when coming to a stop. Usually when you do you have a sticky TP linkage setup. Kickdown band (2nd gear band) is only on in 2nd. When slowing down it should never engage unless you manually pull it in to 2nd or stay on the throttle while pulling a grade and force 2nd gear with throttle pressure.

Closed throttle coming to a stop if you really work at it you may feel a slight bump around 1-2 mph but that’s rare most of the time.
Make sure the throttle pressure linkage is free and adjusted properly and a return spring is usually found on the TP lever to trans case.

Try shutting OD off and see if this bump disappears, it shouldn’t make a difference. The direct clutch in the OD unit comes on when OD come see off but the ORC in the OD should prevent any bump.

One other thing that I have seen is on two piece driveshafts the slip yoke at the center bearing can hang up on the splines.
Coming to a stop and depending on rate of decel the yoke can hang up on the splines then snap free/forward giving you what feels like a shift.