My phone (iPhone 13) gets very hot when using the app in the car. So much so that it stops charging to prevent damage, which is quite worrying. This doesn’t happen when using other apps - eg Google Mops, Sygic, Calimoto. I don’t notice it when on the bike, presumably because the phone is cooled by air flow.
I always have the phone on charge when using navigation apps, as they all drain the battery quickly. The phone is connected to a 2.3 amp usb charger on the bike, I not am not sure the rating of the car charger. I do make sure there are no other apps open.
It seems that Navigation Next requires an excessive amount of power, more than comparable apps.