I keep them muted too, so I get it. But watch someone on a work call the second the microphone light goes red. The whole face reorganizes. My colleague was smiling, nodding, saying "totally, totally" and then she hit that button and her mouth just fell open into a flat, exhausted line, like a rope somebody let go of.
Her shoulders dropped an inch. She rubbed both eyes with the heels of her hands. Then the light went green and the face came back up, snapped into place, "so anyway, to your point."
There is a whole person living in that muted half-second. The real one. The tired one. She rents out the polished version by the hour and keeps the actual face for the mute button.
I used to find that a little sad, the two-facedness of it. I don't anymore. Up there the air you're breathing, the entire sky, every storm and sunset and lungful anyone has ever taken, is a skin thinner than the shell of an egg wrapped around a rock, and it holds. That's the trick of it. It looks solid from below. From above you can see how little there is between the warm part and the nothing.
So a person who can hold a smile for an hour of a meeting she is exhausted by, and only lets the tiredness show in the dark second when the mic is off, is doing the same thing the planet does. Keeping the fragile part covered so the work can go on.
Watch for the drop. That flat second before the light turns green.
That's the one you'd miss her by.