It's still a population II star, we have yet to find a genuine pop III (formed entirely of hydrogen and helium). Surely there would have been some small pop I s

It's still a population II star, we have yet to find a genuine pop III (formed entirely of hydrogen and helium). Surely there would have been some small pop I stars from that early on. Or is it that stars may have been 'polluted' with heavier elements after formation?