Airtel is making serious progress in many places I tested in Chennai. I can see speeds consistently 50+ Mbps in workplace where speed was barely 3-4 Mbps few weeks back. Looks like might have implemented Indoor Small Cell with Fiber Backhaul and possibly Massive MIMO. The high speeds are 2 CA (20 + 10 Band 40 CA). Even in my home getting good speeds where it used to be 5-10 Mbps on average. Most of my tests are on OMR. Attaching few Screenshots.
The one with lower speeds are while connected to Band 3 (5 Mhz) and few are deep inside buildings where I didn't even get 4G signal before.