Shows you exactly where your Performance Max ads are appearing - for instance a junk mobile app or low-quality site taking an unusual share of impressions - using Google's placement data, so you can exclude the placements you don't want and steer spend toward quality. (Performance Max is Google's automated campaign type that runs across all of Google's inventory, and it doesn't volunteer this information.)
Placement impression share - flag a single placement taking more than this share of a campaign's impressions. Default 10%.
Checks weekly. This rule is off by default - switch it on per your appetite for PMax scrutiny.
