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Shouldn't cause an issue either way. Moving from http to https is one of those edge cases. But basically, it's a login page so link equity really isn't a factor (most of those links are likely to be ignored or devalued anyway) and it's not really a reciprocal link. My advice - don't sweat it.

I would usually say no but so many sites seem to link to that same page they are viewing... If you are doing it for schema markup in Google SERPs all their examples show linking to the last part of the breadcrumb, see google rich snippets If you want to inform users you can examine adding a text element for the last part but most just leave the last part as the page you are viewing.