The new Picture in Picture Availability setting can be used for more control over the PIP window. It can now automatically be dismissed when leaving the Guide view or leaving the app.
For example, to recreate a more traditional guide where PIP is used only for live TV channel surfing:
Settings > Playback > Picture in Picture > Automatic: Live TV
Settings > Playback > Picture in Picture > Availability: Guide
Available via TestFlight and beta apk: