Huawei, Samsung, OnePlus
Spotify version 18.104.22.1684
Harman Kardon Towers with Google Assistent and Spotify
My Question or Issue
Normally the volume buttons on my Android phone control the media volume of videos/media that I play on my phone. Lately, however, the volume buttons control Spotify volume when music is playing via the Google Assistant HK Speakers (increasing/decreasing the HK speakers, not my phone). You can see in the screenshot how there's a casting symbol for volume control. I know it is the Spotify app and not Google Home or Chromecast, because when I go offline on Spotify the music keeps on playing on the Google Home HK Speakers, but i can't control the volume via my phone anymore.
So, how do I set the volume buttons on my phone to control the media from my phone instead of the volume from the Google Home HK Speakers?