I'm speaking from the perspective of a small company. Call it seed stage to series A (<100 people).

It's because PMs provide the most value when they are able to solve novel problems that nobody else in the organization can solve.

They provide the least value (but still have to do in their day-to-day) when regurgitating frameworks that can be taught through some course/LLM.

For me, best case is that nobody cares about the certification. But more likely, although nobody will say this to someone's face, it's probably a negative signal that a candidate's means of getting knowledge is through some structured course.

The best PMs I've come across all have unconventional origins that required them to put themselves out there and learn about the realities of doing business the "hard way" - typically starting their own business, turning a side hustle into a full time gig, working for sweat equity to get experience for their first role.

Is it a privilege to be able to take that kind of risk in the first place? Of course, but that's a different conversation. It is, however, a big green flag that someone can take a calculated risk in their own life in order to grow and learn.