u/lumberteeth

Maybe I'm late to the game, but this is the first I've heard of this. Apparently, Sleeper updated it's Terms of Service about 3 weeks ago, and the new terms "say that third-party products accessing Sleeper data for commercial purposes need Sleeper’s express written consent, and that third-party access generally requires a separate agreement or approval from Sleeper."

Yahoo sprung there changes on developers by surprise (what a complete execution mess that is), so it's worth expecting this may be coming from Sleeper too.