This seems to be becoming a common theme with some airlines as well to in theory to minimise any additional risks on the virus being carried on any additional surfaces carried into the cabin. Whether makes any sense or actually reduces any risks who knows given most of the time you can get the impression governments WW are making things up as they go as they have no real idea either how to manage this.Only Air india connecting flights are allowing to carry hand baggage while other domestic flights are allowing only 1 check-in bag of 20kg (no cabin baggage allowed and only one handbag per person which can fit below the seat) They are not allowing to carry extra baggage also.
When asked why so strict and their response was it's a SOP for domestic flights given by the ministry of Aviation.
Always I guess check with airline beforehand as guidelines changing all the time given not good to get to the gate and have to checkin carry on that might contain thinkgs do not want to go in the hold, laptop, camera, medication etc...