I certainly do not know the root cause of your problem. I have a hard time conjuring how break-in for a new vehicle has anything to do with it. I've got a 2 month old '17 Impreza Premium HB and have not experienced this issue. I am impressed with the CVT Subaru tranny....and I've got a '16 Outback too. Computers these days control our outcomes. Deal with it...election results, hacking, paying bills, your electric service, most everything. And a computer controls those shift points in your car.
Years ago I experienced major work computer issues, doing 3D CAD design and 3D part printing. The IT guy trying to fix things did the chimpanzee shrug, and said maybe it was a cosmic ray that compromised my computer. I thought this was the lamest excuse, until I researched it a bit. And yes, an awry, subatomic particle coming from deep space can whack your Impreza computer and turn a 0 into a 1, or vice-a-versa. **** happens, my friend.
Like the advice in the Apollo 13 movie, work the problem. And I'd start with the dealer....you're in warranty, and they should, or could fix this. There's not a lot of problems showing up on this forum with CVT issues. You got hit...maybe by a cosmic ray.