FaceID doesn’t work with sunglasses on either. It would be nice if we could just have both to cover most weather scenarios. Of course too much face covering and gloves in the winter and neither are going to work then (;
You can turn off "Required Attention for Face ID" in the Settings as a workaround.
When FaceID was announced, they also said it should also continue to work with varying amounts of facial hair - which I have also found to be true.
Never had any issues; especially if you setup the alternate appearance with a mask / partially obstructed face.
If you turn off "Require Attention for Face ID" in Face ID settings it'll work with sunglasses.