Can't mute volume/speaker on Samsung A02s during a Twitter Space

I am using a second phone to host Twitter Spaces from a branded account, so that I can speak in the event with my personal account. The branded account will never be used to speak, it is used to just host. I tried to reduce the volume on the phone used for the branded account, a Samsung Galaxy A02s, to zero. Because with any bit of volume there's a terrible feedback loop between the two phones I am using for the Space. However, the phone will not completely mute the audio. I can't mute the phone by pressing the volume down to zero. I can't turn the volume for the Twitter app to zero. I can't find any way to silence the app in settings. I am at a complete loss. How can I completely decrease the volume on the Twitter app to zero?