What? How? Why are all these tinfoil hat conspiracies turning into reality ... like your TV or alarm clock spying on you.
Defenses are either cat&mouse electronic warfare or shielding the walls/floor/roof of some rooms (e.g. research labs in business, industrial systems, home offices, bedrooms) with materials like aluminum radiant barrier or expensive drywall (e.g. QuietRock) designed for RF shielding of SCIFs.
Prior threads: https://news.ycombinator.com/item?id=31561338#31563572
With multiple signals, not only do you get multiple data points on signal loss, you also get a phase difference between the signals (i.e. a signal that passed through you is delayed a bit compared to signal that didn't pass through you). By integrating that knowledge from various signals (or rather 'channels') and probably doing a whole lot of other smart stuff, potentially some training / fingerprinting (i.e. if they are at position X, then the signals do Y, for many different positions), you can get location data.
802.11bf is a thing. It doesn’t seem completely out of the picture for such a technology to be abused once it is implemented.