Would you point out any previous disputes between the head of State and the Ambassador of two close allies, whereupon thehead of State ostracised the ambassador, and in effect his government.
Would Trudeau have done the same to the Australian ambassador, or vice versa?
I think not.
I agree there is nothing new. Foreign diplomats frequently report matters that the head of State does not particularly like. That is their job.
Trumps puerile reaction, however, is new. And imbecilic.
I can't remember specifics, but there have been cases of problems between ambassadors and the elected head of government. Possibly between Canada and the US. I would have to look it up.