I'd like to know how Omar obtained citizenship.
She either took the naturalization test after she was 18, and that should be documented, or she derived US citizenship from one of her parents once they became a citizen and Omar was still under 18. I've seen two birth dates reported for Omar. One is 1981, then after questions about her citizenship came up, it was changed to 1982.
Sauce: https://halturnerradioshow.com/index.php/en/news-page/news-nation/does-ilhan-omar-hold-congressional-office-illegally-citizenship-in-question
Not sure how reliable the website is, but looking at the graphics on that page of how the MN legislature page was altered to change Omar's birth date, it looks to me that what they were trying to do is bump the birth date ahead to claim she was still under 18 in 2000, but not go too far to make her ineligible to run for US senate (35 age min) in 2018. Were talking Somalia birth records for verification, so good luck getting reliable documentation.
I think the problem is that the parents weren't in the US long enough to be naturalized until 2000, and going by the 1981 birth date, Omar would have been 19, thus not eligible for derived citizenship. Might be missing some condition, so here's some sauce on derived citizenship rules for interested lawfag types:
https://www.kwvisalaw.com/citizenship/citizenship-derived-from-a-parent/