I am playing the latest snapshot 1.16 20w16a of Minecraft in Survival Mode and Normal Difficulty(not peaceful). I have built a simple Mob Farm following an episode of pixlriffs (here is the link). For some reason, even after maintaining a distance of 24 blocks, fully covering the spawning blocks, building the spawner in ocean, There are almost no mobs spawning. Here are some screenshots taken in the game. Can anyone help me figure out the problem?
So, as Kcats commented, I was hitting the mob cap, so no mobs were spawning. After rebuilding the spawner at y=194, It's working at decent efficiency.