I had a private family Slack instance, and we observed similar things. A question about buying a particular brand of soap would be spoken in the channel and ads for that exact soap would show up minutes later on Facebook. No searches or other activity, just a text query to a person through Slack.

I prefer to think that some of this is chance, or Facebook just guessing really, creepily well. But after the 3rd or 4th time we observed this same scenario play out, trust has eroded, even if I have no evidence as to how this is happening. It's time to change up the tools.

I now self-host an open source chat application, and we have not had another repeat of this kind of creepy ad invasion.