: Mixing access.DimensionTypeAccess from into .dimension.DimensionType : Mixing access.NoiseGeneratorSettingsAccess from into .levelgen.NoiseGeneratorSettings : Mixing MixinNoiseGeneratorSettings from into .levelgen.NoiseGeneratorSettings : Mixing common.NoiseGeneratorSettingsAccessor from into .levelgen.NoiseGeneratorSettings : Transforming net/minecraft/world/level/levelgen/structure/Structure : Renaming method structure(Lnet/minecraft/tags/TagKey Ljava/util/Map Lnet/minecraft/world/level/levelgen/GenerationStep$Decoration Lnet/minecraft/world/level/levelgen/structure/TerrainAdjustment )Lnet/minecraft/world/level/levelgen/structure/Structure$StructureSettings to structure_$md$89d4cd$0 in :access.StructuresAccess : Mixing access.StructuresAccess from into .Structures : Renaming method byg_create(Lcom/mojang/serialization/Codec )Lnet/minecraft/world/level/levelgen/feature/stateproviders/BlockStateProviderType to byg_create_$md$89d4cd$0 in :access.BlockStateProviderAccess : Mixing access.BlockStateProviderAccess from into. : Renaming synthetic method lambda$keepRichSoil$0(Lnet/minecraft/world/level/block/state/BlockState )Z to md89d4cd$lambda$keepRichSoil$0$0 in :KeepRichSoilMixin : Renaming method byg_invokeRegisterBlockStates(Lnet/minecraft/core/Holder )V to byg_invokeRegisterBlockStates_$md$89d4cd$2 in :access.PoiTypesAccess : Renaming method byg_invokeRegister(Lnet/minecraft/core/Registry Lnet/minecraft/resources/ResourceKey Ljava/util/Set II)Lnet/minecraft/world/entity/ai/village/poi/PoiType to byg_invokeRegister_$md$89d4cd$1 in :access.PoiTypesAccess : Renaming method byg_invokeGetBlockStates(Lnet/minecraft/world/level/block/Block )Ljava/util/Set to byg_invokeGetBlockStates_$md$89d4cd$0 in :access.PoiTypesAccess : Mixing access.PoiTypesAccess from into .ai. : Renaming method byg_getBY_BIOME()Ljava/util/Map to byg_getBY_BIOME_$md$89d4cd$0 in :access.VillagerTypeAccess : Mixing access.VillagerTypeAccess from into .npc.VillagerType : Renaming method byg_create(Lnet/minecraft/world/inventory/MenuType$MenuSupplier )Lnet/minecraft/world/inventory/MenuType to byg_create_$md$89d4cd$0 in :access.MenuTypeAccess : Mixing access.MenuTypeAccess from into .MenuType : Mixing access.BlockEntityTypeAccess from into. : Mixing EnchantmentMixin from into .enchantment.Enchantment : Mixing inject.MixinEntityType from into .EntityType : Mixing inject.MixinFluid from into .material.Fluid : Mixing MixinBlock from into .block.Block : Mixing BlockMixin from another_ into .block.Block : :BlockMixin: Class version 61 required is higher than the class version supported by the current version of Mixin (JAVA_16 supports class version 60) : Mixing BlockMixin from into .block.Block : :client.BlockMixin: Class version 61 required is higher than the class version supported by the current version of Mixin (JAVA_8 supports class version 52) : Mixing client.BlockMixin from into .block.Block : Mixing inject.MixinBlock from into .block.Block : Mixing inject.MixinGameEvent from into .gameevent.GameEvent : Renaming method create(Lnet/minecraft/resources/ResourceLocation Lnet/minecraft/resources/ResourceLocation )Lnet/minecraft/resources/ResourceKey to create_$md$89d4cd$0 in :access.ResourceKeyAccess : Mixing access.ResourceKeyAccess from into : Renaming method byg_invokeRegisterSimple(Lnet/minecraft/resources/ResourceKey Lcom/mojang/serialization/Lifecycle Lnet/minecraft/core/Registry$RegistryBootstrap )Lnet/minecraft/core/Registry to byg_invokeRegisterSimple_$md$89d4cd$1 in :access.RegistryAccess : Mixing access.RegistryAccess from into : Renaming method enhancedCelestials_invokeRegisterSimple(Lnet/minecraft/resources/ResourceKey Lcom/mojang/serialization/Lifecycle Lnet/minecraft/core/Registry$RegistryBootstrap )Lnet/minecraft/core/Registry to enhancedCelestials_invokeRegisterSimple_$md$89d4cd$0 in :access.RegistryAccess
I had to update directory mods, so I suspect it's because at least one of them.