Most popular platforms are tracking and spying on you. My friends and I also believe Slack private DMs are compromised as we often times see ads directly pertaining to oddball discussions we don't have outside of Slack.
Most people here probably know this already, but you can minimize some of this by using privacy browser extensions [1], containerized browsing [2], a good VPN [3], and/or Pihole [4].
I'm curious about the Slack thing. I wonder if there could be third parties doing something (browser plugins, third party keyboards for Android, edit: someone using a TV as a computer monitor.)
One thing is for certain, if ad targeting is not being done in ways it shouldn't be, there isn't anything technically preventing it.
It could be as simple as links. People drop links in the slack discussions, other people from Geolocated IP addresses (or same) click on them. Google analytics et. al. hovers a lot of data.
Most people here probably know this already, but you can minimize some of this by using privacy browser extensions [1], containerized browsing [2], a good VPN [3], and/or Pihole [4].
1: https://duckduckgo.com/compare-privacy?tab=extensions
2: https://support.mozilla.org/en-US/kb/how-use-firefox-contain...
3: https://docs.google.com/spreadsheets/d/1CRtEQzSVE59jj5ROKZlt... (*do your research, e.g. NordVPN creeps me out with aggressive advertising practices even though they're highly rated)
4: https://pi-hole.net/