Disable “coarse location” option in settings. Might not work though.

If you want coarse location to work but don't want Google to know it, try microG with a non-Google location provider (I use Apple and Mozilla and it's pretty good).

www.GrapheneOS.org

Usa an iPhone?

Doesn't Apple do something similar however? When you turn WiFi off on your iPhone a prompt appears saying that it's better to turn it on for "better location tracking" or something like that.

Keeping Wifi on allows “find my” to work more accurately, which many people value. Third party apps such as YouTube have an additional permission to be able to look at the local network.

Newer wifi chips allow passive scanning while the bulk of the silicon is powered down. I.e. it could/should also work in flight mode

On Android, find Location Services in your system settings and look for Google Location Accuracy. The description for it on my Galaxy S21 reads:

> Google's location service improves location accuracy > by using Wi-Fi, mobile networks, and sensors to help > estimate your location. Google may collect location > data periodically and use this data in an anonymous > way to improve location accuracy and location-based > services. > > Turning this off will result in your device only using GPS > for location. This may impact the accuracy of location > used by apps such as Maps and Find My Device.

Based on that description, that should turn off the data collection, although it can also make GPS fixes take longer, and there may well be other apps collecting this data as well.