How did ancient India lose its massive scientific and academic edge? Was it a sudden collapse or a slow fade?

I’ve been reading a lot lately about ancient and classical Indian history, and honestly, the level of scientific output back then is blowing my mind. It wasn't just mystical philosophy; there was a hardcore culture of empirical science, logic, and debate, for example, you had Aryabhata proposing a rotating earth centuries before Europe did. You had Panini structuring Sanskrit so methodically that it essentially mirrors modern coding logic. There were texts detailing complex surgeries (like the Sushruta Samhita), and entire philosophical schools (like Nyaya) that existed purely to study epistemology and test claims with strict logic.

But as someone trying to piece the timeline together, I'm wondering: what actually happened to this specific culture of rigorous science and debate? It obviously DECLINED sadly, but the "how" and "why" feels really murky to me.

I’d love it if someone could help me understand:

1. When did the drop-off actually happen? Did this intellectual output crash during a specific era, or did it just slowly fizzle out over several centuries?

2)What were the main causes? I often hear people simply blame foreign invasions, but how much of it was external destruction versus internal changes—like shifts in religion, cultural priorities, or rulers pulling their funding?

3)What happened to the education system? How did the on-the-ground teaching methods shift away from this heavy debate and science focus before the British eventually showed up and introduced their own system?