If I use Cicles engine everything looks great (obviously). I try Eevee engine with perspective camera mode, and result also fine. But I need ortho projection. If I switch to Eevee + orthographical camera the shadows are absolutely terrible, here you can see.
I use (and need) Sun-light, and try increase Shadows Cascade Size to max value 4096, and result is still awfull:
Any ideas how to fix it? Blender 2.93.3
Many thanks for any help.