But its manufacturing output has still grown substantially because India's overall GDP is expanding rapidly.
I think economic might is tightly integrated to national defence, so this discussion is warranted. As long as we don't overdo it and anger the mods too much.
On the topic of India's GDP, it deserves to be mentioned that there are many doubts about how accurate their numbers are. India's former Chief Economic Advisor, Arvind Subramanian, wrote a series of papers in 2018-19 on this very topic. His estimation is that the official GDP growth number is inflated by maybe 2 percentage points.
That said, I am modestly optimistic about India. We have to compare India to countries like Pakistan or Bangladesh. China is culturally completely distinct. And when comparing India to its natural comparators, India actually does pretty well. I am not a "superpower India" booster, but I think it's almost inevitable they will get to the 3rd largest economy in the world and the distance to the 4th largest will grow as the decades go by.
And one final word on defence. We can laugh about Tejas and whatever, but India is a nuclear power and basically faces no real external threat. The fact that the IAF is a joke is a minor embarrassment, but in the grand scheme of things it's frankly inconsequential.