What is https://..../users/sign_in.zip? What is the function of this zip file? Can I delete it?

I am using self-managed GitLab version 14.5.2.
May I know what is " https://…/users/sign_in.zip" about?
How about /assets/webpack/*.js.gz? Is it only backup files? Is it OK to remove?

Where do do see that file? Why do you want to delete it?