Minecraft wiki entry for Development_versions, associated text: MC-236609 – New mountain biomes use translations strings in biome selection.
MC-236614 – Adventuring Time advancement still accepts non generating biomes.
MC-236617 – Mountains and gravelly mountains use their 1.17.1 biome ID name.
MC-236632 – Banners without patterns do not render properly.
MC-236663 – Command blocks do not display command in their UI.
MC-236736 – No relief on treasure map or explorer maps.
MC-236894 – Foliage from specific biomes can generate in biomes they aren't meant for.
MC-236896 – Strange mini broken aquifer walls generating commonly on the surface.
MC-237490 – The bottom parts of aquifers aren't always surrounded by blocks which can occasionally cause them to spill into caves in ways that appear bizarre.
MC-237586 – Entities that die outside of simulation distance remain frozen in the death animation.
MC-237666 – Unused biomes still present in game files.