Minecraft wiki entry for Development_versions, associated text: MC-236740 – Server-side lag spike sometimes occurs when attempting to locate a buried treasure or opening/breaking a chest containing a map.
MC-236764 – Lighting lags behind world generation.
MC-239397 – Lava pockets generate in icebergs.
MC-239610 – Severe world corruption due to 1.18 snapshots failing to deserialize chunks that 1.17 loads fine.
MC-239682 – Out of memory crash: World generation exhausts Java heap space.
MC-239950 – Feature placement doesn't check for biomes, causing unnecessary lag.
MC-240483 – Foxes that spawn in grove biomes aren't the snowy variant.
MC-240589 – Game froze for several minutes and then crashed while flying around and loading chunks.
MC-241245 – Generated Deepslate overwrites ore veins (mainly Iron ore veins).
MC-241255 – Gigantic Performance Drop after a couple of minutes.
MC-241352 – Directory structure is not consistent between server and client.