US foreign policy has been pretty consistent since the end of world war 2. Whatever you may think of what is going on, it is a significant departure from traditional us policy.
In fact the very foundation of Canada is a response to the US threat.
So yes. I agree there is an actual change vs. the post WW-II trajectory. At least in the public sphere. I don't know what used to happen behind closed doors. AI here says a lot of power struggles have happened (some specific examples but I'll spare you) but not in public. But argues that the shifting of those into the public sphere is a real change. And I agree with the AI overlords.