In this picture you can see the light passes through a window and ends on a surface… unfortunately you can see a lot of tiny points on the surface, but the glass is transparent. I don’t know why this happens: shadow resolution and strenght are at maximum.
What you’re seeing is the result of working around the shadow mapping’s limitation that it is (almost, but not exactly) all-or-nothing in the shaders.
I’m assuming you’re using the Standard Transparent shader, which supports a rather fascinating form of shadow casting. Specifically, it’s using a 3-dimensional dithering texture to generate shadows based on the alpha value of the texture/color casting the shadow.
The texture consists of a black and white texture (all or nothing), ranging from completely unshadowed to shadowed (0-1) for its z-axis depth, then following dithering patterns to add more and more interwoven pixels to transition between colors across the x and y axes.
If you are willing to eliminate the shadow completely: You could put the glass on a layer that is ignored by the light (light’s culling mask field). This way it won’t cast any shadow (alas, NOR be lit normally).