65 interviews and rejections in 10 years? If the potential employers know that or can see it on your résumé that's a red flag. But I wouldn't expect you to get past initial screening if they can see that history.
Interviewers are frequently advised not to give feedback or criticism because of the risk of lawsuits. Anything they tell you potentially can come back on them, so they say nothing. I have been through several classes on interviewing and hiring conducted by lawyers and they always advise to say nothing, to never give a reason for not hiring someone beyond the vague "We don't feel like you're a good fit" or "We found a more suitable candidate." At least in the US the legal risk probably explains why no one will tell you what's going wrong.
You're getting to the final interview, so it's probably not your résumé or any obvious red flags during the initial screening process. Failing so many final interviews indicates there's something you're doing (or not doing), not just an occasional glitch at a few companies.
If you think back on some of those interviews, was there a point where you knew, or at least sensed, that the interview had gone bad? A look you got that communicated discomfort, boredom, lack of interest? I know I have sensed that moment when I know the interviewers have decided to hire me or not -- they either relax a bit and the talk gets more casual, or they go silent and start going through the motions. If you can replay interviews in your head and think about what was asked and said just before that moment, what you might have said, how you responded, etc. And think about how you talk to people, what kind of impression you make, your body language. As objective and "technical" as companies try to make their process look it still comes down to "Did the interviewers imagine working with me?" People tend to make such decisions quickly (within just a few seconds of meeting someone) and based on superficial characteristics, then the rest of the interview is normal human rationalizing to confirm the decision they've already made.
When I've made this point before people have argued that interviewers don't make snap judgments, and the process they follow is more objective. But imagine if someone shows up for an interview late, or dirty, or drunk, or starts the conversation by slapping you on the back, or saying "This place was fucking hard to find." You and everyone else has already made up your minds regardless of how well the candidate aces the whiteboard problems or the panel interview. On the other hand, a neat, prompt, attentive, courteous, smiling, and attentive candidate has a lot of runway. I'm not saying you're showing up late or drunk or rude, but think about the impression you make in those crucial first few seconds. Maybe ask a friend you trust to tell you honestly what they think about your demeanor and presentation. A career or interview coach might help, or a good recruiter.