I've never done this, but you might consider getting an experienced interviewer to do a mock interview with you (of the same sort you've breezed through before). It might be a coincidence that you have been rejected multiple times, or it might be some small behavioral thing that someone could tell you about.
Alternatively, you can say "screw this," and I wouldn't blame you.
Huh, I like that idea. Thank you. Possibly a good excuse to get in touch with some former colleagues as well, which I suppose couldn't hurt either.
Mercifully, I'm not quite yet desperate about leave my current role. But I do feel like my career (and salary) progression is stagnant; not seeing much opportunity where I'm at. I'm thankful for what I've got, but I think it's smart to be looking. Just found it weird to face rejection so much from people reaching out to me in the first place, in a supposedly hot market.
Alternatively, you can say "screw this," and I wouldn't blame you.