That is how I have to manage the target output when Pipewire doesn't switch the audio to my Bluetooth headphones upon connection (sometimes it does). The confusing part is that the selected/target output in Settings->Sound on Pop!_OS continues to show as the headphones but the sound from the application, say Firefox, doesn't switch to that (clicking on Test works perfectly which is when I realized that the issue probably was not with Bluetooth/headphones but about per-app switching and tried pavucontrol which confirmed the doubts by showing Firefox output still going to analog stereo).