This might be WAI, but whatever the case, it definitely isn't Java Edition behavior. In Bedrock Codebase, when you bounce off a slime block after falling from a high distance, there won't be any landing particles. I think this kind of makes sense, but I've reported it here to make sure. It should be noted that, if you hold shift to prevent bouncing, there ARE particles, just like any other block.
- Place a slime block.
- Teleport/fly high enough above the slime block so that when you fall there would normally be landing particles with any other block.
- Notice that when you hit the slime block and bounce, there are no particles produced.
- Now fall again, but this time make sure you are sneaking.
- Notice that this time there are landing particles.