Copper&Trident farms in MC 1.21.3 (Minecraft Java 1.21.3+)
Reinforcement based copper farms are broken in the most recent version of Minecraft (1.21.3), and I don't think they can be salvaged. This video explains why they are broken, and gives alternatives how you can still farm copper efficiently.
If you want renewable copper, you can build a traditional trident/copper farm but rates will be capped at around 800 copper ingots/h. Much faster farms can be built in large river biomes in perimeters, the 2-player farm presented here in the world download gives almost 7000 ingots/h (4500 in the singleplayer version). But rates can be higher or lower depending on the size of your farm (size of the river biome).
Honorable mention is a quarry, whose primary purpose is not copper production but that might satisfy your copper needs, especially if you drive it through a trial chamber.
Notes:
The changes in the item pickup system in the latest snapshot (see Xisumas video, • Minecraft 1.21.4 Snapshot 24W45A | Collars... ) might solve the issue with the "eternal" tridents, eliminating the need to push in the 2 blocks in the kill chamber for 20 seconds. But it still can't hurt to build this :)
Referenced videos:
IanXOFours reinforcement based copper farm: • Minecraft Elegance: Next Generation Copper...
1.21.1 fixes and optimizations for Ians farm: • Copper farm 1.21.1 updates/fixes (IanXOFou...
Traditional trident/copper farm: • Easy trident/copper farm using the magic o...
Ncolyers fast trident/copper farm: • Minecraft Trident & Copper Farm - 120+ Tri...
Docm fast copper farm: • Hermitcraft Season 9 - The BIGGEST Farm i...
Hermitcraft 9 world download: https://hermitcraft.fandom.com/wiki/M...
Fast creeper farm with Methodzz pickup: • 1 million gunpowder per hour? Fast creeper...
LogicalGeekBoy and Methodzz explain the height map: • Dissecting Minecraft #10: Mob Spawning Par...
JKMs quarry video: • How To Build The Ultimate Quarry In Minecraft
My take on the quarry: • Quarry time! Building and storage. Hemisph...
World download:
singleplayer version https://www.mediafire.com/file/39xs3n...
2-player version https://www.mediafire.com/file/3cvplv...
Chapters
0:00 Reinforcement based farms are dead
4:28 Quarries
6:51 Traditional trident farms
8:30 Perimeter copper/trident farms
10:27 Drowned farms are SLOOOOWWWW
12:28 Basic farm layout
13:23 Kill chamber
15:24 Singleplayer version