From what I know, its partially because of how taxation structures incentivize research as R&D tax breaks or similar don't particularly exist in India

All of this makes founders more likely to move abroad where such research is more valued which makes even less Indian deep tech startups and successes exist. This creates a vicious cycle.

I would also consider that Indian VC scene as compared to America undervalues quite decently even for B2B or even supposing identical companies and even then, Sequoia and some other American VC firms are still the most valued and I feel as if that given their expertise and contacts (other companies that the VC's have invested in being in America), there would be a slight push towards Europe/America in general. Another argument could very well be that in India CS engineer labour costs much less which is honestly some of the largest expertise for any company.

Though Indian VC scene is thriving and Bangalore is interesting but still Silicon valley is different.

There was a blog post which talked about VC dynamics and VC's value your product not on how much the real value they really see in the project is but rather on how much money you would require. So ironically, projects which require larger budgets/funds for researching, larger salaries to work would then have larger valuations.