It's not just an American thing - the same thing does happen in the UK as well. Most new African immigrants also tend to look down on Africans and Caribbeans born and raised in the UK as well.
However, I wouldn't call it xenophobia because it's a mixture of their own insecurities, ignorance, and the narrative they got from the media. You need to understand that most Africans on the continent view the west as the paradise where opportunities abound. So, once they get to the west and see synthetic aesthetics that are superior to where they came from - they always develop a complex and suddenly believe the opportunities are endless, without knowing that there's a ceiling for black folks because they don't understand systematic/institutionalized racism. Obviously, when they start meeting the black folks who have lived in the system for generations, with nothing much to show for it, in poverty - coupled with the media narrative - it's normal for them to swallow everything hook, line, and sinker and start looking down on these folks.
Overtime, after spending decades living in the same system and getting more acquainted to how things work and the fact that everything is make-believe...they tend to come back to their senses.