The same thing just happened to me. I’ve been using a hidden login page for months and it has worked fine. Now when I try to go to that page, it redirects me to my homepage https://www.nylacrystal.com
I did the WP update and everything was working fine until this morning. Probably happened in the same time frame as fellene, who posted above me.
Anyone have a fix for this? I don’t want to go deleting stuff from the directory folder. My site is functional, I just can’t login ??