To be fair over the last 10 years it’s gotten a lot easier as they know the expectations and they’re thinking about the security implications of their apis.
But it’s kinda fun to explain it to a new dev or pm, and no, it has to be done before any preview release.
There are days when I wonder if what I do is worthwhile and then someone comes to me with questions they’ve prepared for and thought through potential security problems and solutions.
But the real fun is intern security reviews. Our interns write real code which can become part of the product so midway through they get a security review and I won’t give them answers, I give them research so they can figure it out. Usually works too, sometimes it’s too niche and I guide them.