So, why has no fix happened with Spotify to fix the annoying flickering when a user is using GSYNC? Only way to keep it from happening is to turn off hardware acceleration which can affect sound quality.
I realised the spotify I had installed was the Windows Store application one. I uninstalled the Spotify from the windows store and downloaded Spotify from their official website. This version of Spotify fixed the problem for me. (just did it a few seconds ago).