Question

In order to prevent discrimination against applicants of protected classes, your colleague decides to note the protected class characteristic of the applicants on their applications. what would be your advice to her

Answer 1

I think noting the protected class characteristic of the applicants on their applications would not be a good idea in this context.
By doing this, you literally Created a chance for racism to happen (because the applicant handler could determine the race/ethnicity of the applicants)