Bedrock not changed to Deepslate in Experimental world, walls of bedrock in new caves

I changed an existing world to caves and cliffs generation, and the bedrock layer has not changed to deepslate. The new caves generated outside existing chunks are made of normal stone instead of deepslate, and the bedrock from existing chunks continues down into the new caves, creating bedrock walls.
Latest version of Bedrock, running on iPad Air 4. (iOS 14.6)