Bedrock generating at Y level 0

I don't know if this is a bug or a new update I don't know of but I started a hardcore and was trying to get to the Deepslate part of the caves (y level 0 and under), I was then hit with bedrock at y level 0?! Can someone explain. This has also happened to some of my friends and i would like to know what's going on...

(btw this is on part 1, so I apologise for this 'bug' if this gets fixed or is just a feature.)