Issue with Sort By field on job applications

I cannot understand the criteria behind the "Request Info Update - New to Old" filter.

For example, within a job requisition with all the applications in the "NEW" stage if I filter for "Create Date - New to Old" the candidates are sorted by the date they applied; but, if I filter for "Request Info Update - New to Old" the candidates are sorted another way, but I don't understand by what criteria!

Please help me,

Thank you in advance,

Lorenzo