One striking example was when I solved the coding problems posed to me in 15 minutes out of the 45 available, the interviewer said "that's great, I don't have any more questions, please use this time for you to ask about the company" and then the recruiter told me I was rejected because I did not do the coding part well enough.
That's terrible behavior from the interviewer. Did you try raising this with your recruiter?
You can come off as the most awesome person to work with, but they'll typically reject you if you can't solve the leetcode problems to whatever minimum standard they're expecting.