I’m raising the BS flag on this, at least as written ... a GPS application would need the satellite signals to compute your position. I dont know of many facebook users that have a GPS antenna as part of their desktop.
There has to be missing info in this article/warning.
That’s what I was thinking, the only thing I can think of is that it extrapolates your general location from the IP address.
If you use FB on your mobile, it would tag me all over the place. I turned off the GPS locator on my cell as well
I believe they can get the info from your IP address.