I think there should be an icon shown above a player when they voluntarily mute/disable VC from the voice settings menu.
When a player mutes themself, the existing muted mic icon should show above the player.
When a player disables their VC entirely, either use the existing "Player is muted" icon or make a new icon similar to Discord's "deafen" icon

Will be available in 2.X.X
https://i.imgur.com/tgNng4h.gif