Could you please check if you've deactivated the option "Process my Facebook data" in your Spotify Account? You can find it by visiting https://spotify.com/account/overview > Privacy Settings > Manage your data > Facebook data
Thanks for the screenshot. Since you've signed up with Facebook, Spotify needs to process Facebook data to correctly display your profile name. Please try switching on "Process my Facebook data" and close/re-open your Spotify app.