Then I found a thread in the FB forum that talks about exactly this. The general response was that FB is particularly sensitive to people transferring credit card points especially if you accrued those points by activities that didn’t involve flights.
They also talked about the fact that the danger is greater if you’re using those points to get flights for others beside yourself.

I wasn’t aware of this myself, and I don’t know that there’s any way to check if other airlines do something similar without checking the forums for each airline.