Hide users in voice channels on phone activity

Alright so, I got in touch with Discord support and they told me to post it here. Because I actually thought it was a bug but they claim it works as intended, which I think is a bit weird.

I create a private voice channel in my server (which is a community server) and make sure it is hidden from everyone, except me and a friend. Whenever me and some of my friends join the voice call. Other users who do not have access, nor can see the channel, can still know we are there and if we stream or not by using their mobile device. They can just navigate to their notifications and look at the activity feed.

Now to me this seems weird, I make these calls private for a reason, no? I dont want people to still see us by some work around using their phone, or am I totally missing something here?

If this is how it is suppose to work I'm suggesting a change, or at least let me control whether or not I want people to see this.