Console versions also work like this, rearview always had the transition animation. It takes around two seconds to finish it. (RVGL reduced it to one second)
► DC rearview before transition
► DC rearview after transition
Instead of disabling the transition, I would just prefer having new chase view for look back (similarly to F2 mirror, but not as zoomed in to the car and better height) when chase camera is set as default, and keep the old rearview (with transition) when hood/first person is default.
However with a much better view angle of a *new* view, it would give a great advantage in certain pickup races and most battle tags, so unsure about it's implementation.