Hi, for a few days I was looking for my issue but unfortunately not found.
This glitch seems to disappear when I switch from Forward to Deferred rendering, but on deferred rendering everything looks different, badly, I’ll need a lot of time to make it look similar to my settings on forward rendering.
Here is video which shows my issue:
As you can see, not only shadows have this problem, grass also flickering with bush made of planes.
Forward rendering with gamma color space.
It’s not problem with camera near clip plane, it not removes this issue.
I need to fix this issue, this is crazy annoying when moving around 
Other problem by the way:
Also my billboard trees on scene aren’t affected by light, so in night they are bright, only fog make this far away darker. When I remove all light from scene, ambients etc. they have still the same color. (grass is affected by light, only trees don’t)
And trees aren’t affected by global fog shader, only by default fog.