I am not able to login https://oss.sonatype.org/
I also could not login to oss.sonatype.org. However, when I logged in to this community site with my email address and the same password used on oss.sonatype.org I was asked to accept some conditions. Once I accepted I noticed that I could login again to oss.sonatype.org. I’ve no idea if that was related but worth a try.