I checked everything again and tightened x-pulley, it was a little loose. Also 1 belt screw was lose also. Tightened everything, added threadlock to all screws.
I tried to cut the part again, and got exactly the same result. Please see photos. What is interesting, it starts straight and goes to side after 20 passes. Deeper it goes more to side it takes. All my attempts were giving exactly the same curved offset.
MeshCam simulation shows everything right and G-Code senders visualization also shows it straight.