transmission should be a value between 0 and 1, representing the fraction of light passing through. I’m not sure what a larger value like this will do.
Usually values closer to 0 or closer to 1, as opposed to somewhere in the middle, will make the limited resolution of the transmission render target less obvious. There is no other workaround for the moment, see Is there a way to set roughness transmission mipmap resolution? - #3 by donmccurdy.