In this article from MacRumors by Joe Rossignol, there’s this:

“The amount of location data collected by apps while in the background has dropped by 70 percent since iOS 13 was released, according to Jason Smith, chief business officer of data intelligence company Location Sciences.”

Having dropped by 70 percent is a tremendous impact that should make one sit up and take notice. I’m not surprised since when one calls attention to something, it tends to make others a little more aware of what’s actually happening with their data.