Interesting. Both of my Ts referred to us as "us" many times and I personally liked it - it gave me a sense of collaboration. I do the same often with my own work colleagues now, learned it from the Ts. But only in a professional context.

Well, when the T that I had some nasty conflicts and shaky boundaries with used this expression, it evoked some negative emotions, but what I hear in it is still primarily the fact that it's something that we created together. It bothers me much more if they refer to the ambiguous or negative message using "you, you and you" in it - that gives me a sense that they are not taking responsibility for their own part.