Movable Translucent Object Much Brighter on Mobile Platform

I use a translucent material for character’s eye. But I find out that the eye will remain bright when I use ES3.1 preview even there is no light at all.
here is how it looks like:
But it looks correct when I close the preview:

It seems like there is a light cache when I use mobile preview.

Any ideas how to fix this? Thanks a lot.