I didn't realize how messed up internal systems were during the interviews or what group dynamics actually were in real life. I judged too much from the hiring manager and the best of my colleagues whom I still think highly of. I thought I could make a difference and they paid really well (not FAANG).

What changed was a combination of realizing how little I could actually do, magnified by a whole new tier of VPs hired from Microsoft and Google who brought their loathsome ways with them. One never expects the Spanish Inquisition...

Do you think this is a problem with the hiring process or impossible to avoid things like this?

It's impossible (IMHO) to avoid things like that. In this situation, I couldn't predict the future - hiring a new "leadership" (gack!) that transmogrified the organization I joined.

Sometimes companies allow people to try a role/team for a handful of weeks before committing. Would that have helped?

No, because I couldn’t time share with my previous employer.