Shadows have weird dots/lines

My tree prefabs seem to have a weird thing going on with their shadows, light seemingly passes through them, creating weird dotted lines. I'm making a low poly stylized game so I don't mind the hard shadows, but the dotted, pixelated parts of the shadows bother me.
I've tried changing up some shadow values to no avail.

Here are some an examples:

https://imgur.com/a/KiUCh69

Any help would be appreciated. Thank you.

 

Try turning on doublesided shadows on the Light.