One tweak they could make is that mutants only appear from people who were (or were not) 'snapped' out of existence by Thanos, making them a subset of an already odd class of people who've returned to a world that's had five years go by without them (and many, if not most, having lost just about everything during fives years presumed dead, come back to find their homes occupied by strangers, their kids grown up, elderly relatives dead, their spouses remarried, their jobs taken over years ago, etc., etc.).
Having the mutants only appear from those 'snapped' (or only those who got left behind), could make for a funky sort of 'us vs. them' distinction, and lead to notions that they 'came back wrong' (or that those left behind were tainted somehow?).