Wow...I basically never let webpages use my location, but I did for this one, and it landed about 200 feet from my apartment. That's crazy accurate! How can an IP be linked to a geolocation that closely?
https://www.andygup.net/how-accurate-is-html5-geolocation-re...
If you're on mac and have an iPhone, same thing is happening across the whole OS.
Available WiFis, even if you're not connected to one, will be used by your OS to provide location as well.
This uses the basic Geolocation API, you can look up how your computer figures out its location for more detailed info.
If you don't have Wifi on, maybe you had it before, and Google saved your location based on it?