Probably. On the other hand, it would be a stretch to say that a system that takes 20-25% of it's trainees from overseas is systematically biased.
There was an interesting study some time ago where identical resumes were submitted, one with a "white" name and the other with a "black" name. Predictably, your name influences your future employer in the expected manner.
All sorts of baked in biases affect residency matching, just like life. Diversity goals of current US University leadership is interesting. It reflects "US" diversity, not world-focused. Which makes sense, in a certain way. But is just another bias in another way.