When I opened my survival world in 1.18, I found that some of the bedrock at the bottom of the world had not been replaced by deepslate. The survival world was created multiple versions ago.
Expected behaviour:
All bedrock at the former bottom of the world is replaced with deepslate
Actual behaviour:
Some bedrock blocks which generated around y=3-6 aren’t replaced
Device info:
iPad 9th generation
iPadOS 15
We are tracking this issue at MCPE-149251. If you have a copy of the world from before you opened it in 1.18, please attach it to MCPE-149251 or upload it to a file-sharing site like OneDrive or Dropbox and then share the link.