Steamdeck - 1.0.0n
I bought the hieroglyph voucher on Ante 8 small blind shop with the Violet Vessel as the Final Boss Blind. It set me back to ante 7 and changed the scores required, but the boss blind was still violet vessel (score required of 210,000 on red stake).
Regardless if this is an actual bug, it definitely is strange since if you use hieroglyph voucher on ante 9, it gives you a final boss blind because you're on ante 8.