Afaik nearby wifi networks are also used to determine location. As long as you have wifi activated Google can use this to determine where you are. I don't know if they use this as a hard check.
The only way I can think of to prevent this is to build a faraday cage with a wired vpn router and your phone inside.
The only way I can think of to prevent this is to build a faraday cage with a wired vpn router and your phone inside.