This is the closest thing I could find in the 2019 Owners Manual. It's purging warm/hot air from the system.
When the outside and interior cabin
temperatures are moderate to high, the
intake setting may default to turn off air
re-circulation to allow fresh air into the
passenger compartment. You may notice
air flow from the foot mode, bi-level
mode, or side demist vent outlets for a
maximum of 15 seconds. This may occur
when previous climate setting was
system off. This is not a malfunction.
After the initial warm air is expelled, the
intake will return to automatic control,
air flow outlet will return to previous settings,
and operation will continue normally.
To exit, press any climate control
It would seem it's designed to work that way, so there's no hack to stop it.