Hey I'm a premium user, I use Pixel 2 XL and right now the Search Bar when you swipe down on the top of the playlist is gone. I can't search for my songs inside the playlist now. That is on android. However I can search it from clicking the 3 dots on right top and click on ''find in playlist'' but I don't care about that. That is not convenient at all! Is this one of the Apple feature things? Like how am I unable to use such basic feature now? What is going on?
If you would like the Search function to be reimplemented within playlists, make sure to head on over here and add your vote to the idea. The more votes that the idea garners, the more likely it is that Spotify will consider reimplementing it!
In the meantime, you can check out this post (which includes screenshots) to see how to access the Search function for playlists.
Hope that helps! Let us know if you have any other questions regarding this.