Realtime Shadows on Terrain Trees & Grass Issue...Can someone help me?

https://youtu.be/-AU2lbuKyhg

Hi everybody! In this video I show you my Realtime Shadows Issue and I have no idea how to fix that... I tried to set the Near Clipping Plane from 0.3 to 0.5 on the Player Camera (and i have also the far Clipping Plane set to 11000 because of visualize the Texture of the moon on a day/night cycle),set Four Cascades Shadow on Quality Settings and setting on the Mesh Renderer of all Objects in the Scene (and also the Trees) Cast Shadows On and Receive Shadows On like I see in other post on this forum but this didn't solve my problem...Can someone help me please? >.<

PS the Render Mode on the Directional Light is set to Important and the shadows are set to Soft Shadows in Very High Resolution

PS If I remove Grass from Grass Editor of the Terrain the Shadow Flickering stop... but I don't think that the Issue is due to Terrain Grass... and I also need the Grass on the Terrain (it's more realistic)