Facebook could quite easily use that data to draw more connections between people. Who they work with, who they might know within the same teams and enterprises, etc. etc.
[1] https://medium.com/delta-cx/facebook-bought-giphy-but-doesnt...
The article basically says that Slack made a special case for Giphy, and so they decided that Giphy in particular doesn't get the same treatment as your typical slack bot or slash command.
So, all FB needs to do is block that integration and either force their own or negotiate a new setup with slack. "You have a command called giphy and giphy is our trademark, so stop."
The article you link to explains all of this, so I don't think you've refuted my point, really, except to say that it doesn't happen right now.
Signal goes to great lengths to preserve privacy with their giphy integration: https://signal.org/blog/signal-and-giphy-update/
Why did they allow acquisition of Instagram and WhatsApp then? Makes zero sense to me.
And if Facebook is not allowed to buy other social networks then Chinese will buy them. And then again we will be in the same situation just like we are with TikTok and Huawei. Data going to CCP and not to Corporate America. I prefer Corporate America over CCP to be honest.