How are playlists synced across devices when library syncing is off?

I'm an Apple Music subscriber and I manage all my music on my Mac. My library is made entirely of locally-stored music files, and I do NOT have library-syncing turned on because I don't want my music replaced with Apple's versions.

My iPhone got damaged, so I'm temporarily using an Android phone. I had copied my music files onto an SD card and put it in the phone already, so I installed Apple Music and signed in. It appeared to scan the phone and find all my music files and add them to the library, which was cool... but I was baffled to find playlists appear. How are these syncing from my Mac to an Android device, when I have library syncing off?

To find out, I went to music.apple.com and logged in. This does appear to be where the playlists came from, but I don't know how they got there. Also, they're out of date and out of sync with those on my computer... and there are some goofy generated ones that don't exist on my computer:

Feeling Happy

Favorite Songs (containing three entries that I don't even remember playing)

My Shazam Tracks

Shazams

Does anyone know how these get created, populated, and synced?