I'm using PC desktop Spotify version 18.104.22.1688.g9064793a.
I was investigating the issue related to constant high CPU usage and memory leak of Spotify app, and accidentally has noticed the strange thing:
If you try to monitor the Spotify process via Sysinternals ProcessMonitor you will see, that every time Spotify starts is reads every file (which even does not belong to Spotify) located in C:\Users\<user>\Downloads despite the fact that all Offline Songs data is being saved to totally different directory by default (according to Spotify settings the path is C:\Users\<user>\AppData\Local\Spotify\Storage).
What the heck is going on ? Why does Spotify app collect the data about all my files in Downloads directory ? What is being done with this data ?