Phones and smart TVs, probably other appliances. My SO used to be surprised to receive ads about stuff we talked about minutes before. I finally looked at her phone, disabled a bunch of things in the stock Android settings, those timely ads went away. I didn't even have to install Blockada, uBO for FF (and uMatrix and other addons) like I do on my devices.

Can you elaborate on what did you disable?

I feel like by disabling ads in most devices, I'm also taking away the best source of information on what bad actors (here ad companies) managed to exfiltrate about me.

If there only was a way to sell ad space about myself and learn from it what others know.