Sometimes, ores that generate in deepslate blobs still generate as regular ores. This seems to be the result of deepslate blobs generating after the ores in adjacent chunks. It can be fixed by just having deepslate (and tuff) blobs replace ores with their deepslate variants.

Attachment 1: A blob of iron affected by the glitch

Attachment 2: Two blobs of redstone affected by the glitch

Attachment 3: The same two blobs of redstone after applying the fix

Attachment 4: The bug is still present in 21w17a