Privacy - Mobile Tells What Voice Chats Friends Are In Even If Servers Aren't Shared

I really dislike that you cannot opt out of this feature. 

The other night, someone was able to follow up on/gossip about mutual acquaintances who were in the same voice chat on a server she thought they had left and it caused drama that never should have happened. She got this information because her mobile phone showed them in voice on said server, which she isn't even on.

The fact that I cannot opt out of friends opening their phones and finding which servers I'm in voice on is pretty annoying. After that incident, it put an even worse taste in my mouth. I hadn't paid much attention to my mobile app until then, and I used my mobile to glimpse my friends list and see a lot. While I knew I could nose around on my friends list I thought it was limited to servers we shared. It's kind of ludicrous just how much I could “spy” on them outside of those bounds, without any way to opt out of that. PLEASE let us opt out of this.