2016 Yukon XL Denali 8-speed Kick at stop

[GregP61]

Transmission is 8L90 (M5U). After driving and trans-fluids hot, a hard kick is felt when stopping and downshifting into 1st. When moved into manual, downshifting 3-2-1 while slowing to a stop does not have the kick. When trans is cold, no kick is present. Complete flush & filter and the TCM checked with no codes.

Any suggestions where to start?