With TIDAL as well as Qobuz, you have a tight integration with the Music Library, so you can see Artists/Tracks/Albums/Playlists/Genres in a integrated way. When you go to Music > Playlists, you will see playlists you have marked as Favorite on TIDAL as well as potentially others from Qobuz or created on Sense. The same applies to the remaining Artists/Tracks/Albums/Genres. Then you can access the specific TIDAL section on Music > TIDAL and if you scroll to my collection, you can find there only the TIDAL items you have marked as Favorite on TIDAL. Naturally if you only have TIDAL configured on the system, these display the same thing. Normally My Collection was added essentially for TIDAL certification as they required for their tests and most users I know just use directly via the appropriate pages on the Music section.
Hope this clarifies.