T-Mobile: Are you blocking specific words and suspending accounts?
PayPal has a similar problem. They do really loose string matching on the OFAC list[1], for any data, in any payment field...even a comment.  Match a magic string in a comment, and your PayPal account gets locked down in a way that's very hard to undo.[1] https://www.treasury.gov/resource-center/sanctions/sdn-list/...