The consumer-facing user agreement rarely applies in corporate settings. Customers negotiate master agreements with the vendor (in this case Slack, or maybe Salesforce) which limit ways the vendor can use their data, and often have significant financial penalties for sharing data without customer permission.

I used to work for a company that handled a lot of classified data. In that space, there’s a notion of something being “classified by amalgamation”. In other words, I can tell you something that is not classified, and someone else can tell you something that is not classified, but you knowing both those things collectively may make it classified. I always wondered how much classified intelligence was leaked to or through Teams in this way. That nobody ever considered it blew my mind.