There’s a red “1” notification on the Settings button at the bottom right, but I have no idea what it is.
Clicking on the button just opens Settings, no markings saying what the notification is related to.
Poking around a couple of settings didn’t reveal anything.
On Android, v2.24.0
FIXED - It was a notification that an upgrade was available.
I suppose this is what is fixed in 2.24.2: https://github.com/aeharding/voyager/pull/1845