yes! obviously That depend on Data speed.
U r getting 15-20mbps on avg , so no buffering will be there definitely.
and on the other hand, I m getting 3-4mbps and Getting buffering Symbol on hotstar..but on that same data speed , Prime Video streaming at 1080p, youtube streaming @720P, streaming voot, voot kids also... no problem!
Only problem with Hotstar.
And I think not only me, but also lot of users facing this kind of problem..
Source- Comments section on hotstar app.