Minecraft wiki entry for Development_versions, associated text: Some fields in worldgen structures that previously only lists of element IDs now accept tags.
Those entries now accept [id, ...], id (shortcut for [id]) and #tag.
Changed fields are:
feature.glow_lichen configuration: can_be_placed_on
feature.spring_feature configuration: valid_blocks
feature.simple_random_selector configuration: features
block_predicate_type.matching_blocks: blocks
block_predicate_type.matching_fluids: fluids
biome: inner list in features, map value in carvers
biome_source.checkerboard: biomes
Some tag fields now require id to be prepended with #, however they are not yet accepting element list:
dimension_type: infiniburn
feature.geode configuration: blocks.cannot_replace, blocks.invalid_blocks
feature.vegetation_patch, feature.waterlogged_vegetation_patch configuration: replaceable
feature.root_system configuration: root_replaceable
structure_processor.protected_blocks: value
Structure fields in noise settings no longer have separate subfields for strongholds and non-stronghold structures. Instead each structure has a tag field which is tag: concentric_rings for strongholds and tag: random_spread for non-stronghold structures.