Thanks for the input.
The people from the lab said that it is emulsion scratch. I could not see the scratch on the frame for the gate check because it is too bright. But I was able to see the scratch appearing more clearly as the camera rolls from the bvery beginning of the shot of the slate.
The light leak has coloration. The light leak begins on the right side of the frame from the begining of the role. Untill the middle of the role, the leack stays only on the right side of the frame. It is constantly blinking. From the middle of the role, the scratch begins and colaration happens on both sides of the frame. Coloration and scratch disappears at some point and do not appear again till the end of the role.
Could this happened by the misloaded film?
Thank you everyone.