Wanted to make sure I'm not missing something. On PS5, when you tap the PS button and access Spotify through the music tab at the bottom of the screen, there is no option to listen to liked songs. The only options are Featured on Playstation, Recently played, Spotify recommends, and Your music (which only includes your playlists, not your liked songs).
When listening to songs, there is an option to add a song to your liked songs, but again, there is no way to play them without opening the full app. This was an option on PS4, perhaps this was just overlooked?