I upgraded my nexus 6p to oreo this week and went out for a ride with the garmin connect app open to browse around for some segments and to do some exploring. My garmni 520 was on and recording the ride, the phone wasn't doing anything fancy. Towards the end of the ride I got some text messages from from my service provider saying I've blown through most of my mobile data for the month. Somehow garmin connect ate through 1.64gb. 1.59gb in background mode.
Screenshot:
https://drive.google.com/file/d/0B-hCWz60F9C2TGhrT1ZZT0xOdzA/view?usp=sharing
Can someone explain to me what the heck? That's half of my data plan nuked for the month.