Searching Liked Songs is Strange

[Grakky]

Using an iPhone the search feature usually easily finds songs by artist or title BUT some songs it finds nothing but produces what took me a long time to figure out is part of Spotify and not an empty result; I get a + sign and then a word. I searched for "I'm Good",  the word that popped up is actually a genre or a mood or type of song. When I touch the + sign or the word (in this instance is Mellow), the song pops up.

After the song pops up and I do a search every single song or artist that has whatever I typed in the search box pops up.

Now when I type in 'David' or "Bebe" then every song or artist with those 2 words pops up, before clicking on + or mellow nothing pops up.

That's strange right?