Music being added to playlist after listening automatically

[TheRealRowanPC]

Plan

Premium

Country

UK 

Device

(iPhone 6s+PC)

Operating System

(iOS+Windows 10)

My Question or Issue

 I'm not sure why, but if I listen to a song on spotify, it will be added to my main playlist after its finished. It appears at the top of the playlist even though I have it in custom order. I have no idea if this is a feature i've accidentally activated or a bug but it's rather annoying. If I listen to a song already in said playlist, the song will move from wherever it is in the order to the top, please help.

Playlist Link: https://open.spotify.com/user/therealrowanpc/playlist/7KXxIoDTfjPVh1EGqQw1J0?si=-v6z9w2gRKWXGZhSzEBY...