If you want to stream games from your PC to the Steam Deck using RemotePlay, you need to follow the steps mentioned in this post.

The Xbox app for PC recently received a new layout and introduced a new section called Recently Played Games in System Tray.

allowing PC games to stream to mobile devices or handhelds like the Steam Deck. It offers superior image quality and latency compared to Steam Link, using the Razer Cortex app and Moonlight client.