use regex::Regex;
fn main() {
 let regex = Regex::new("((?<year>\\d{4})-(?<month>\\d{2})-(?<day>\\d{2}),?)+").unwrap();
 for c in regex.captures_iter("2015-01-02,2025年12月24日") {
 println!("{c:?}");
 for m in c.iter() {
 println!("{m:?}");
 }
 }
}

I'd expect to go over both "2015-01-02" and "2025-12-24", but it seems only the last group retains:

Captures({0: 0..22/"2015-01-02,2025年12月24日,", 1: 11..22/"2025-12-24,", 2/"year": 11..15/"2025", 3/"month": 16..18/"12", 4/"day": 19..21/"24"})
Some(Match { start: 0, end: 22, string: "2015-01-02,2025年12月24日," })
Some(Match { start: 11, end: 22, string: "2025-12-24," })
Some(Match { start: 11, end: 15, string: "2025" })
Some(Match { start: 16, end: 18, string: "12" })
Some(Match { start: 19, end: 21, string: "24" })

Well do you mean you need an output matches of 2015年01月02日 & 2025年12月24日, in that case, your regex pattern is wrong, as it matches all the continuous data matches because of + operator (repetition specifier.)