Thanks man! Now its so obvious.
I did some research and even with 0.4 mm via pad and 0.2 mm via drill i still have the same problem, there is just to much clearance between via annular ring and nearest copper ( I calculated that default setting in KiCad is 0.2 mm clearance ). And there is no way i can route properly without losing my ground plane.
For my design ( BGA packaging with 0.8 pall pitch ) I need at least 0.1 mm clearance.
You can change the clearance settings in within the design rules.
Ground plane clearance is set within the plane settings itself. (Don’t forget the copper min width.)
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