I was just flying around in spectator mode when I found a gold ore instead of a deepslate gold ore this ore is a -55 Y and it's also in the same vein as some deepslate gold ore so I'm fairly certain this is a bug. Edit: I did a bit more flying and found some redstone ore in deepslate redstone ore also at around Y -55, this time it's in a lava pool so I'm wondering if it could do with that. Edit Edit: I found some gold ore that was generated in some tuff and the whole vein was normal it might be because it was detecting the tuff and stone not the deepslate or the Y level and so generated as the normal version (I'm not sure if this is a bug or not now but I'll assume it is) (also I mined out the tuff it didn't generate that way)