Upstream has released updates that appear to apply and compile correctly.
This update has not been tested by PaperMC and as with ANY update, please do your own testing
Bukkit Changes:
9a294519 SPIGOT-7533, 943: Add missing Poses for 1.20.3
be2884c4 Add unique ID to PlayerResourcePackStatusEvent
d9c1eb83 Add additional @MinecraftExperimental annotations
68f5bb6a SPIGOT-7526: Add missing PlayerResourcePackStatusEvent statuses
CraftBukkit Changes:
368c48be1 Fix formatting issue in previous commit
da8f91f31 SPIGOT-7534: Error when chunk with decorated pot trying to save
d20c9291a SPIGOT-7532: Entity#isValid() returns false after server restart
ec1fa2ead PR-1309: Add tests for Bukkit Pose
5a7080b58 Add unique ID to PlayerResourcePackStatusEvent
0fd734950 SPIGOT-7528: Fix certain custom shaped recipes
In general, the client now has an acknowledgment system that will cause block changes made by the client to be reverted correctly.
Essentially:
The client enters a "prediction" stage, where any block changes made will have its old blockstate captured (this is referred to as "server state").
If you update blocks during this stage, the client will update this captured server state as long as they're still currently predicting.
After prediction is done (via an ack packet) all captured blockstates are reverted to their captured server state.
This means that if the server actually updated a block and send a block update packet, it's correctly set, while if a block wasn't updated on the server but WAS updated on the client (server state wasn't updated), that change will be reverted.
It should be noted that this system does not yet support block entities, so those still need to be resynced when needed.
I discovered this when noticing that blocks broken outside of the player's valid interaction distance are still properly reverted, even though the server doesn't send any block updates, only an ack packet.