How to fix shadows with sky light cubemap only?

Hello. For better performance and more uniform lightning I’m using only sky light with cubemap (4k, low contrast). But I see something strange with shadows near gate (something like bright aura around character without darkness):


There is more: there shouldn’t be shadows near gates in first picture:

so I see it only in game.
And another example (only distance has changed):


I tried to change mip gen settings of cubemap, but it doesn’t gave any effect. Can you help me with it?