This nice butterfly is almost impossible to exactly determine from photo.
"Complex Colias hyale" is not a formal taxonomic rank — it is an informal grouping of closely related species that cannot be reliably distinguished, especially from photographs. Within the genus Colias, C. hyale and C. alfacariensis look nearly identical (females and younger individuals in particular); separating them requires genitalia, host plant, or DNA. Curators therefore leave such records at the complex level: it avoids a wrong species assignment while keeping the data scientifically usable. So this butterfly is almost certainly a member of the Colias hyale complex, but the photo alone cannot tell us which species it is.
