Kitty
  1. Have VRChat Android app Installed.
  2. Join a VRChat group that creates announcements frequently.
  3. Verify you get push notifications on your phone with the app closed.
  4. Leave the VRChat group.
  5. Wait for the group to push a new announcement.
  6. Get notified on your phone every time that happens from here on out until you turn notifications off, or uninstall the app.
I receive notifications from at least 3 different groups that I left ages ago.
I'm not sure what kind of announcement needs to be made, or what options need to be selected for this to occur (on the person making the announcements side), but when I go on my PC and check the group (without joining it) I don't see the announcement I saw on my phone, so lets say, theoretically, someone who is in a admin only group gets kicked, they will still receive announcements of that group on their phone, which could be used as a way to spy on people/groups.