It may have estimated location data with IP from Wi-Fi. Location Services turns on GPS but that is not the only way of getting location.

Use a custom DNS and/or hosts file. You can cut them off the grid by blocking data upload to SSP. Don’t install many apps, for games that can be played offline, play them offline. EDIT: AdGuard DNS doesn’t block the 1st URL (o.isx…) in the page. 2nd URL is blocked.