Made a world in 21w08a, and played in 21w08b. In spectator mode exploring the new ore distribution when I came across this vein of one diamond ore and one deepslate diamond ore which generated at y=-1. Not sure if this is a bug, or is intended.
MC-217293
Normal Diamond Ore and Deepslate Diamond Ore generating in the same vein!
Resolved
Works As Intended
0
Works as Intended. From y=0 down it gradually changes to deepslate, meaning that ore at y=-1 can be either deepslate or stone