I had to upgrade to a Pixel 2 last fall and have noticed that I get data usage notification several times a week now. All they say is "Android System / High mobile data usage / Your apps have used more data than usual". Maybe 3-4 times ever it's told me specifically what app was using data. To make matters weirder, I'm almost always on Wi-Fi when I get these notifications.
I've checked "App data usage" in the "Data usage" section of the "Settings" menu, but I'm not getting any info as to what is using data. I've talked to two other people with the Pixel 2 and a Pixel 2 XL and they've never gotten this notification.
I'm using a GSM sim, haven't done anything special to the phone.
Also, honestly, this phone has been using way more data then any of my previous phones. My last one was a Nexus 5X, and before that a Nexus 5, and both regularly used way less than 500MB of data on a normal day, but the Pixel 2 for me has been a huge data suck.
Why am I getting these notifications? Is there a big enough difference with how the Pixel 2 uses data that I'd see this kind of jump?