I think you're right, Frank. It amazes me the modem technology would affect the app, but I know it must given the major app problems going from 2G to 3G. When they weren't ready, they took the easy way out and didn't even consider their customers.
IMO, anyone within the bumper-to-bumper warranty - like you - should be covered at no cost.
I found the directions on how to swap the modem, complete with color photos, in case anyone wants to self-install. Assuming you can get the modem amid this chip shortage. I only found out about this change (with the app de-commissioning in just three weeks) today when I got a push notification.