Swamp slime farm

A slime farm in a swamp, so no slime chunk hunting and no digging one out. The spawning platform sits at the right height in the swamp with glow lichen keeping the light at level 1, which is dark enough for slimes and too bright for everything else, and an iron golem in the middle pulls the slimes towards the hole. They drop onto magma blocks and the drops go to a hopper minecart underneath. You AFK on a scaffolding tower at y 190. Design is moretingz's, Shulkercraft built the tutorial. It is the standard answer for anyone who does not want to hollow out a slime chunk, and it has kept working since 1.19 with two small changes the comments have worked out.

Mangrove swamps work exactly the same as ordinary swamps for slime spawning.
Use brown mushrooms instead of glow lichen, one on every block of the platform. Same light level, and they are what stops skeletons and bogged spawning in there and killing your iron golem.
Name tag the iron golem or it despawns as soon as you go up to the AFK platform.
The AFK platform has to be at exactly y 190. One builder was 4 blocks high and got 31 slimeballs an hour instead of thousands.
A 3 wide bottom slab ring around the spawning platform raises the rate, because mobs spawn in groups and the ring gives those attempts somewhere to land.
It stacks. Repeat the middle section for more layers, and soul campfires at the bottom kill twice as fast as magma blocks.