The original Nikon FTZ mount adapter is now listed as discontinued at B&H Photo. The Nikon Z6 II + FTZ and Nikon Z7 II +FTZ kits are also listed as discontinued. The Nikon FTZ is on backorder at Adorama and is currently in stock at Amazon in case you need the integrated tripod mount that is not present in the new FTZ II version.
The good news is that the new Nikon FTZ II adapter is currently in stock at Adorama and Camera Canada (check also the availability at B&H | Amazon | WEX | Calumet | Foto Koch | Foto Erhardt).