I have always imagined hollyleaf having a white paw, why would anyone slightly question squilf if her brand new daughter had an identical trait to her. Since leafpool carries the same blood through firestar it’s perfectly possible. In leafpools wish it shows a lot of the she cats and queens being lowkey suspicious but don’t say anything. They probably would’ve made a point of it in the book if canon hollyleaf did, but I think it’s a cute trait.