The RCC column was cut in my absence due to passage of pipe for bathroom fittings. The thickness is about 1.5 in. Will it hamper the stability of structure?
Would you believe if someone told you it's ok? I think not.
Because there is not enough information. One needs to know the loads on this column, it's function, what rebars and concrete mix are used in it.
Generally if the rebars are not damaged you can repair the cut with appropriate epoxy mix applied after properly cleaning and preparing the notch.
Many of the building supply places have patching tool and epoxy by reputable manufacturers. One needs to follow their instructions.
I would seek advice from a professional regardless. The entire workmanship and the floor holes look like a careless job.