I have a M1 Pro, same issue. Activated Jan 2024
It’s not mould the screen is sealed all the way round. It’s not green. My front mic works and I can’t imagine sweat going down the hole and across to the camera.
The camera would steamed up if moisture got to it.
It’s some sort of glue seeping out.
The front camera on these model is often where a finger is placed in landscape mode. (I’m left handed but it should apply to right handers)
Maybe the heat from a thumb has softened the glue?
The front camera is still working but the glue is working towards the middle.
I’ll be annoyed if Face ID stops working. Only the Pro models have it and the Pro models cost a fortune.
Curious how many of us are having the same issue and apple doesn’t want to know