This is a little hard to describe, but my Trail Particle system looks different than that of the video.
When I open the particle viewer (or in gameplay) the animation loop starts with multiple spheres emitting in different directions, but then the rest of the loop is just individual spheres emitting from the center and going off in different directions. By contrast, in the tutorial, it looks like it’s a persistent puff of spheres emitting in multiple directions.
The end effect is when the projectile leaves a trail, it looks like it leaves relatively evenly spaced spheres in its path, that doesn’t really look like smoke.
Not sure why this is happening.