More specifically, is there a specific era in India's (extraordinarily long) precolonial history where it was notably and significantly more liberal regarding homosexuality than it is today? To narrow this question temporally, I'm mainly interested in the India of the two or three centuries immediately prior to British rule, but if there are noteworthy instances beyond that then feel free to raise them.
I think part of the problem with answering this question is that "pre-colonial India" describes a lot of people, places and times. I'm not an expert on any of them, but I can say that there were certainly places and times in India when homosexual behavior was tolerated, much in the way that it was tolerated in Ancient Greece and Rome or throughout parts of the Persianate Islamic world. I'm thinking specifically of Mughal rule, which was heavily influenced by said Persian culture, during which homosexuality was seemingly relatively widely and openly practiced among the Mughal aristocracy (the same can not necessarily be said for the common folk). While Islam forbids "unlawful intercourse" these laws were apparently pretty widely ignored (though that was more a result of difficulties arising from Muslim jurisprudence than tolerance):
[T]hese legal provisions were rarely implemented since guilty was very difficult to establish. The Shariah demands incontrovertible evidence, such as confessions or four faithful eyewitnesses confirming that they saw penetration occur . . . The difficulty of finding eyewitnesses to confirm instances of penetration in effect removes private acts between consenting individuals from the realm of punishment.
Kidwai, Saleem. "Introduction: Medieval materials in the Perso-Urdu tradition." Vanita, Ruth, and Saleem Kidwai, eds. Same-Sex Love in India: Readings in Indian Literature. Springer, 2000.
Even the great Emperor Babur wrote in his memoirs about the crush he developed on a boy he saw in the market:
During this time there was a boy from the camp market named Baburi. Even his name was amazingly appropriate. I developed a strange inclination for him – rather I made myself miserable over him.
Before this experience I had never felt a desire for anyone, nor did I listen to talk of love and affection or speak of such things. At that time I used to compose single lines and couplets in Persian. I composed the following lines there:
"May no one be so distraught and devastated by love as I; May no beloved be so pitiless and careless as you."
So while this certainly wasn't the case for all of India at all times (or even all of the Mughal Empire), it isn't unreasonable to say that the current prejudice and discrimination against homosexuals in the country isn't necessarily inline with how Indians have treated the matte historically.