I've experienced this once and lately someone told me something like this too.
For example, someone you work in a project that you have frequent discussion with, let's say they are in a different department and you really think that their team and your team is cooperating well, like they give good feedback and approves/disapproves stuff openly, good discussion flowing. But then when there's a meeting they suddenly act like a stranger, acting like cold and distant, but then after the meeting they acted normally again like the meeting never happened.
In personal matters I kind of understand that this thing is kind of normal.
Is this kind of act normal, like accepted as acting professional?
Maybe on lower level this thing is more personal, but what about when you are acting in higher level management, like say you're a head of x department, have a good relationship with y , in meeting you acted coldly against y , but then outside meeting it's all good again.