I have no idea how to replicate this. As you can see, my score exceeds rank #1. Of course that's impossible caus I'm honestly not good, nor have I used any mods other than hard rock on this song since I haven't played it much. Seeing this I got curious what'd happen if I scored higher, so I played it again to get a better rank on it.
It seems to have fixed itself, and it was obviously cosmetic, but I've no idea what happened here. The number it gave me for the score looks like it was given to me at random, but comparing it to the other scores it's not a score that'd seem impossible to achieve on this song. I've no idea where the value came from nor how it applied itself to my puny B rank. On my public scores list the B rank that's shown doesn't seem to appear at all. It's as if it never existed.