Only cobbled deepslate can be crafted into polished deepslate, tiled deepslate, deepslate bricks, etc, whether that be in the crafting grid or with the stonecutter.
Normal deepslate is effectively worthless, and now a bit annoying to turn into the more useful cobbled deepslate if you have a silk touch pickaxe.
Thank you for your report!
We're tracking this issue in MC-222728, so this ticket is being resolved and linked as a duplicate.
That ticket has already been resolved as working as intended, which means this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.
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