What makes it not a democracy ?

a form of government in which the people have the authority to deliberate and decide legislation ("direct democracy"), or to choose governing officials to do so ("representative democracy").

Going by wikipedia, India fits in as a representative democracy. None of the elections are contested despite widespread corruptions. Its pretty much assumed all major parties do so and thus in a level field.

Where most have issue is:

Features of democracy often include freedom of assembly, association, property rights, freedom of religion and speech, citizenship, consent of the governed, voting rights, freedom from unwarranted governmental deprivation of the right to life and liberty, and minority rights.

India has some level of trouble with almost all of those. Both in past as well as some ongoing.

A large part of the reason is all available government choices are shitty in some sense or other. Modi is bad but so was their opposition. India didn't start having these issues magically the day modi came to power. In that sense many blaming him ignore how deep rooted these problamatic views are in general soceity (at least in some areas and communities).

My point is that the many issues pointed here stems from a deeper problem and exists despite India being a democracy not because it isn't. Infact if it was nearly as authoritarian as many claim, it would have plunged into greater chaos.