My Minecraft world is still with bedrock at y=0 to -64

I updated my world to 1.18 and i was hoping that the bedrock would be replaced by deepslate but it didn't.

Mouths ago I changed my Minecraft to beta 1.17 and entered my world, and after a while, i changed to the normal Minecraft to play in servers. I think that might be the reason for this
I don't know what to do