Ghosted after 4 Rounds

So I’m a PM, close to 2 years of PM exp in BFSI post my MBA (from a top 20 Indian BSchool) I lucked out in my last org and my current one due to some reasons which is why I’m actively seeking PM roles

I came across a great opening, got in touch with the hiring HR. Gave 4 rounds over a course of 1 months and haven’t heard from her in a while (3 interviews and 1 assignment submission)

I want to know how common is this behaviour? I’ve followed up with her multiple times (risking my negotiation power later since she will know I’m desperate) but to no avail

It’s a good role in my hometown and the company also seems to be doing good + my current role is ruining my mental health which is why I was so keen

I honestly don’t know what went wrong as I kept on getting good across all rounds