Bedrock not getting replaced in worlds that already had the "Caves and Cliffs" toggle before 1.18.

Hi. I been excited to hope that my bedrock will be replaced after 1.18 come out, however when I loaded up my world and checked if the bedrock stayed or not, it stayed. I updated my version to 1.18, but I only see bedrock and not Deepslate. The bedrock is naturally generated too.