Open the Your Likes playlist in Youtube Music in a web browser (not the mobile app).I was able to migrate my Likes from YTM to Spotify as follows:

However, YTM doesn't expose 'Your likes' as a normal playlist, so Soundiiz doesn't have any access to it (and nor would Spotify if they were to develop a similar feature). I used Soundiiz to transfer all my other playlists (it works great and was well worth the $4 I spent to do this). I have over 6K songs in my 'Your likes' YTM playlist and have been frustrated that I can't migrate those to Spotify. Well, that's my two cents, and it just really is discouraging to see all of these recommendations to use some random third-party services. But still, it can be done, it's just parsing serialized data exported from another service. I understand it may not be a trivial engineering effort, especially with UX, due to lots of differences in features for managing a music library. The Spotify platform itself is honestly not enough reason to switch (so far, IMO). I'm currently still just trying Spotify out, but this lack of support is such a major factor in the decision. Users spend years cultivating a music library with one platform, and it's a PITA to have to manually re-do all of that work. The lack of support for importing from another service has been a major pain point and blocker for me to switch over to Spotify. We're living in times where data privacy and cybersecurity are more important and vulnerable than ever, and the solution is to use some third-party service's portal to login to multiple accounts and pass all of our data through their servers?

It really is a bummer that Spotify doesn't offer a means to import music library data from other services, and worse, users are referred to other solutions which involve utilizing some third-party service. Transfer from Google play music/youtube music to S.

Convert youtube playlist to spotify