Why gas stove burner omits greasy soot all over inside building?
If the gas is burning a blue flame there is nothing in the gas causing the problem. If it is orange then it will create soot but not grease. What you describe sounds like oils evaporating from the cooking and condensing, the soot bit is charred or partly burnty oils from the cooking. Cooking oil is cooking oil no matter the quality so it will be a ventilation problem – you need to extract the smoke/ evaporated oil from the pans to the outside.
