Mine used to have a hard down shift from 2-1 when coming to a stop.
It was most pronounced when it was a 'rolling stop'. If I grannied it by coming to a complete stop every time, it rarely did it.

Last year as part of my overhaul of my X5 I complete an AT filter change and fluid change with the BMW spec fluid. Since then, I haven't felt the dreaded hard downshift.

Not sure if that will help your problem, but it did help mine.

Good luck

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2005 X5 4.4i black on black
2003 325Ci black convertible