I have built a raid farm as I always have for over a year now (lower trident killer for patrol spawns, upper spawn platform and trident killer for raids) but since one of the more recent updates Pillager captain spawn rates have severely decreased, when a raid is finally triggered it will randomly cancel for no reason and I've had them spawn in a 1x1x1 hole filled with lava.

I have literally covered the entire outpost, anything in or around it that could be classed as a spawn spot (buttons, levers, torches, etc) and a large area around it at ground level in leaves and the only way to get to the afk spot is with scaffolding. Unfortunately I have no other information that I can give you as I've not changed the design for the farm since 1.17.