I normally have GPS and Bluetooth disabled, so my position would have to be guessed based on cell towers. We were not even on the same WLAN (because the WLAN was down in the vacation home, much to our dissatisfaction).

While I can't rule out somebody in our group stealthily googling the tablets, phones while playing is generally frowned upon.

So yeah, being on the same cell tower as someone I know who might have searched for it might be the only other explanation.

The adventure itself didn't have anything to do with the tablets, that was just our group doing strange stuff, like always.

Conformation bias. You think of something and you see more of it. You don't realize the 1000's of other times you have seen that. Do you honestly remember every add you ever see? No but when you have thought about something you are more likely to see more of it. Or do people purchase more or your colour or type of car after you get it? Or is the fact you see more of them more likely because you are now "looking" for them.

Just think about the scale of the surveillance: every smartphone user is being monitored 24/7 in hope to find something to sell them.

If you hate AI because it wastes so much energy, think about the cost for the this: Energy, water, battery life, bandwidth, ... And in contrast to AI the 'users' don't get anything in return.