When I talk with managers, there are several things I can count on them saying (and believing) that are almost always not true. It isn't because the manager is clueless (there aren't delusional Michael Scott's). They simply don't realize reality because it is hard to see.
One area is about feedback. Most managers believe that they give enough feedback, that their feedback is incredibly clear, and that their team has no qualms about giving feedback to the manager.
Let me respond - you don't, it isn't, and they do.
I could give you dozens of real examples that I've witnessed personally where managers were flat out wrong about this - and less than 5 where a manager was right.
The only way to know if you have a feedback culture is to have an outside party evaluate it (who knows what they are doing) and to consistently worry about it.
Keep in mind - when a manager says "my team knows they can tell me anything and that I want honest feedback and disagreement", they are only fooling themselves.
It is one of the reasons I say managers know the least about what is happening in their own department among the team.