There are too many to list. An online search is a better idea.
Here are two instances:
Google was (and probably still is) tracking your location on Android even when you turned off location services and storing it against your account.
Google signed you in automatically into Chrome whenever you signed in to a Google property. This change removed the ability to keep your Chrome browsing data strictly locally. After some Internet outrage, this was reversed.
For specific technologies: Their search engine. Their Ad network. Google Maps / StreetView. Android OS. Google Home. Google Nest. Google Chrome. Chromebooks.
