Cursor with clustered particles - Cannot uncluster

We saw this cursor that got a trail after dots after it. We are eager o know/learn how to recreate this!

https://drive.google.com/file/d/1aRwDElwnBffvlLiJVAHEEpg0021JpY1G/view?usp=sharing

We managed to get the moving particles. But our version got this cluster of particles next the cursor that we want to simplify and dial back on the cluster animation.

https://drive.google.com/file/d/1DuSH3a-8y6sMvfE70HDk8UxgwTiwOhiE/view?usp=sharing

We cannot seem to find out the code that’s creating this cluster. Can anyone point us in the right direction please?