Sounds like you work with inexperienced PMs that are not doing their job, did you try having a serious conversation about this pattern with them? I'm pretty sure some communication would go a long way towards getting you on a better collaboration groove.

I've been doing API development for over ten years and worked at different companies. Most PMs are not technical and it's the development team's job figure out the technical specifications for APIs we build. If you press the PMs, they will ask the engineering/development manager for the written technical requirements, and if the manager is not technical, they will assign it to the developers/engineers. Technical requirements for an API are really a system design question.