Please, take a look at the picture below:

Why the shadows are like these? I put another question regarding shadows in another forum, but no one answered.
EDIT: just to complete: I made a map with some blocks (the path, the field), the big rocks I made with blocks too, the big mountains with a terrain creator, the trees are models, the leafs are sprites. The rocks in the path (field, whatever) are blocks together.
Anything is not single mesh. I JUST dont know what is going on.
I have 3DGS Extra and I spent 2 days trying to work good with shadows. This is getting very boring.
Thank you.