Today frontpage started to say the same. I figured I'll test from a different IP and even login worked.
Seems like the some mistake might have led to some potentially incorrect ranges getting blocked.
@dang, for reference, it is the IP that ends with 109.205
It seems it was a little overzealous a little while ago which even made it false flag people navigating through the index, but luckily dang and the team seemed to have fixed that (I happened to be one of the victims and reported it...)
Anyway, you can unban yourself -just once- by following https://news.ycombinator.com/item?id=4761102. Note that you have to do this from another IP than the banned one, like a mobile device on 5G instead of your home wifi so keep your phone or tablet handy.
If for some reason the algo flagged your IP again you are SOL and need to contact dang through the Contact link below.