Unless they've changed it in the last 45 minutes, the first line of the description says: "Powered by WebRTC and SFU integrated server." and "SFU" is a link to the Mediasoup website.
Edit: I see the mediasoup project is also listed by name in the credits section. So I rescind my earlier comment. I still think it's a fine line to call this project itself an SFU though.