From Felipe Carvalho on Twitter:
After today, you can add as many songs as you like to your Liked Songs on @Spotify I’ve been working with a small team on the refactoring necessary to pull this off for a while now. Very happy to see this finally out.
This definitely falls into the Finally™ territory, as I’ve been complaining about this for years now. Really happy they finally listened to users who hit the cap a long time ago and have had to come up with creative ways to get around it.
A little too late for me though as I recently moved back to Apple Music and have been very happy there.