Very unlikely. There is a massive payday for the first person to find a major bug. Even if that bug does not result in extra crypto in your pocket, doesn't matter. Its trivial to make money on downward crypto price swings as well. Find bug, take short position, release bug, collect payday.
Probably not in scope for Project Zero? Or they find other stuff more interesting.
Security researchers don't work for free. I did some light searching and I couldn't find any sanctioned audits against Bitcoin core. The Bitcoin team should hire someone like trail of bits to do a multiple month audit.
But the "security researchers" wouldn't be working for free. Bitcoin has had an enormous bounty on its head for at least 10 years: "hack me and get paid millions/billions". It would be naïve to think there aren't highly skilled people continuously trying to do that.