How do you share WiFi over usb / hotspot, not cellular data.
When the devices are connected to your personal hotspot, and your phone is connected to WiFi, data should not be used for the hot spot.
Question marked as
Best reply
If you have connected to the Hotspot you are consuming Cellular Data.
Your iPhone is connected to the internet through the Personal Hotspot of another iOS device.
Your iPhone is connected to the internet over Wi-Fi.
The Hotspot is a Carrier Specific feature. Contact your Carrier (Cellular Service Provider), the agency that issued the SIM / eSIM to you.