New Features in 21w05a

Azalea bushes as well as flowering azaela bushes!
Added cave vines and glow berries!
Added drip leaves!
Added decorative blocks for the upcoming lush caves: hanging roots and rooted dirt!
Added moss!
Added spore blossom!

Cave vines and glow berries

Cave vines grow down from the ceiling, like weeping vines
When they grow they have a chance of producing glow berries
Glow berries are a natural light source as well as a food source
Foxes eat glow berries
Use glow berries to plant new cave vines
Bonemealing a cave vine will create glow berries

Dripleaf

Small dripleaf needs moisture, so it grows on clay or underwater
Small dripleaf grow into big dripleaf when bonemealed.
Big dripleaf grows taller when bonemealed
If you stand on a big dripleaf it will tilt after a while and you will fall off
You can crouch or jump to prevent a big dripleaf from tilting
A tilted big drip leaf will tilt up again after a while
The big dripleaf will break when hit by a projectile
The wandering trader will sometimes sell small dripleaf plants

Moss

Two new decorative blocks: Moss block and moss carpet
Moss carpet can be crafted from moss blocks

Spore blossom

A beautiful large flower placed on ceilings
Particles drip from it

Changes in 21w05a

The stonecutter can be used to craft the different copper block variants
The stages of copper oxidization are now called "Copper Block", "Exposed Copper Block", "Weathered Copper Block" and "Oxidized Copper Block" in sequence of least to most oxidized
Drowned now have a chance of dropping a copper ingot, they no longer drop gold ingots
Added new sculk sensor events
Changes to powder snow

Sculk Sensor Changes

Added the following game events that the Sculk Sensor reacts to, along with corresponding frequency value:

Vibration Types	Frequency Value
Minecart Moving, Ring Bell, Block Change	6
Drinking Finish, Prime Fuse	7
Mob Interact	8
Equip, Shear, Ravager Roar	9
Entity Place	12
Entity Killed	13
Shulker Close	14
Shulker Open	15

Block Change is for when player or dispenser action has changed a block. Example: cake slice being eaten.
Mob Interact is for specific mob interaction events that cause vibrations.
Prime Fuse is for both TNT and Creepers.

Powder Snow changes

Flaming arrows now get extinguished when they collide with Powder Snow
Skeletons now convert to Strays when frozen
Powder snow is now pushable by pistons and sticky pistons
Foxes can now walk on top of powder snow without falling in

Technical Changes in 21w05a

Improved performance when using many overrides on an item model
Copper oxidization is now a random tick effect and thus affected by the randomTickSpeed game rule

Fixed Bugs in 21w05a

MC-9568 Mobs suffocate / go through blocks when growing up near a solid block
MC-130098 Debug world spawns player at y=2 instead at y=70 where all the blocks are
MC-142711 Baby turtles take damage when pushed against ceiling
MC-148432 Sound spam while in water and lava at the same time
MC-149495 Pufferfish triggers tripwire without colliding with it upon reloading the game
MC-152265 Starting server outputs "unable to resolve BlockEntity for ItemStack" errors
MC-153254 Baby zombies/piglins take damage when pushed against ceiling by bubble columns
MC-163673 Baby husks, piglins, zombies, zombie villagers, and zombified piglins take damage when jumping into a space with a solid block above it
MC-186879 Standing in fire and water spams the extinguish sound
MC-191714 Player is dismounted when standing on farmland while riding a horse/boat while the farmland turns to dirt, causing a desync
MC-198432 Pufferfish phases through blocks after reloading world
MC-199356 chatDelay in options.txt has a space between the colon and the value
MC-200906 Pufferfish hitbox incorrect when reloading world
MC-204801 Large amounts of copper blocks lag the server and causes the worldsave to take forever
MC-205079 Cauldrons don't fill with powder snow in some biomes
MC-205401 "Fire extinguishes" Sound repeatedly plays when a mob that burns in daylight is in powder snow
MC-205477 Occasional desync when trying to enter/exit a boat while the server is lagging
MC-205735 Baby cows can suffocate on stairs
MC-206113 Powder Snow causes Z-Fighting with Falling Blocks
MC-207258 Sculk sensors do not react to minecarts being driven
MC-207261 Bell ringing event is not considered a vibration
MC-207262 Drinking potions or milk doesn’t cause vibrations even though eating does
MC-207263 Inconsistency: Filling cauldrons with liquids or powder snow is not detected by sculk sensors
MC-207277 Sculk sensor can't detect setting a fire with fire charge
MC-207283 Extinguishing a campfire is not detected by sculk sensor
MC-207300 Blocks being placed or picked up by an enderman are not detected by sculk sensors
MC-207329 Sculk sensors don't properly detect eating from other mobs
MC-207340 Sculk sensors do not detect buckets of fish being emptied
MC-207358 Sculk sensors don't detect shulkers opening and closing
MC-207384 Flame arrows repeatedly trigger sculk sensors
MC-207387 Sculk sensors can sense players sneaking in water when they move, even when they're not swimming
MC-207391 Sculk sensors don't detect certain flying mobs
MC-207397 The fire extinguish sound plays every tick when the player is on fire and freezing
MC-207407 Villages will always generate at least on y=0
MC-207417 Directly breaking fire does not alert sculk sensors, but removing its supporting block correctly does
MC-207418 Breaking paintings/item frames/glow item frames does not alert sculk sensors, even though placing them does
MC-207445 Sculk sensor doesn't detect squids swimming
MC-207473 Sculk sensors do not detect when ghasts shoot
MC-207520 Sculk sensors don't react to ravager roars
MC-207521 Ocelots and cats can still emit vibrations while sneaking
MC-207592 Shooting bow with flame enchantment while sneaking triggers sculk sensor
MC-207600 Sculk sensor detects wrong sound for fishing rod
MC-207670 Sculk sensors do not detect the placement of boats and minecarts
MC-207671 Sculk sensors do not detect candles being placed into cakes
MC-207672 Sculk sensors do not detect when creepers are set off with flint and steel
MC-207673 Sculk sensors do not detect lighting TNT with flint and steel
MC-207674 Sculk sensors do not detect placing things in flower pots
MC-207675 Sculk sensors do not detect books being placed onto lecterns
MC-207677 Sculk sensors do not detect collecting water with bottles
MC-207678 Sculk sensors do not detect collecting honey bottles
MC-207679 Sculk sensors do not detect the breaking of bee nests and beehives in Creative mode
MC-207745 Sculk sensors do not detect when ender dragons shoot fireballs
MC-208193 Sculk sensors do not detect removing things from flower pots
MC-208194 Sculk sensors do not detect when candle cakes are eaten
MC-208477 Going into a dimension that has height higher than the maximum height crashes the game
MC-209361 Game crashes upon instantly click-replacing the block underneath a bamboo sapling with another bamboo
MC-209625 Baby llamas suffocate when below a solid block while standing on top of a carpet
MC-212117 Placing glow lichen in lava creates waterlogged glow lichen
MC-212141 Shulkers get rotated when upgrading to 21w03a
MC-212149 Shulker is sometimes mis-rotated when player teleports through a nether portal and reloading an active chunk with Shulker
MC-212284 Crammed enitities pushed through blocks when growing to adults
MC-212290 Commands "setblock" and "fill" don't work at or above height 1024 in some cases
MC-212291 Client can dismount vehicles independently from the server, causing a de-sync
MC-212331 Boats dismount you in the direction the boat is facing instead of the direction of the player
MC-212347 Importing custom world file height is limited to 2047 instead of 2048
MC-212422 Game crashes when generating a world with increased height limit
MC-212532 Shulkers are spawned slightly mis-rotated after a shulker was hit by another shulker's shulker bullet
MC-212537 Standing near a shulker slightly lifts you when they open
MC-212541 Shulkers are often incorrectly rotated upon generation
MC-213512 Copper blocks are named differently from bedrock edition

Minecraft Snapshot 21w05a