Minecraft wiki entry for Development_versions, associated text: MC-240481 – Deepslate doesn't generate in the new cave generation under old chunks.
MC-240482 – There is no bedrock in the Overworld in old chunks.
MC-240495 – Deepslate does not generate below Y=0 in badlands or wooded badlands biomes.
MC-240503 – Bedrock doesn't generate in badlands or wooded badlands.
MC-240516 – Cave carvers don't generate below old chunks.
MC-240531 – Block simulation distance is always 8 chunks regardless of the slider's value.
MC-240534 – Clicking a JFR link copies full server-side path to clipboard.
MC-240631 – Extremely slow End terrain generation.
MC-240998 – Portals no longer load chunks as non entity processing.