Just to add: Scanning networks to gather data seems pretty popular these days - smart tvs have done so, and even the ebay site used to portscan visitors [1].
[edit] And of course, there's WebRTC leaking your local IP - which ublock origin can specifically block [2].
[edit] And of course, there's WebRTC leaking your local IP - which ublock origin can specifically block [2].
[1] https://www.bleepingcomputer.com/news/security/ebay-port-sca...
[2] https://github.com/gorhill/uBlock/wiki/Prevent-WebRTC-from-l...