Why do some particles end up more transparent when emitted

Why do some particles end up lighter or more transparent than others when they are emitted? I don't have any rotation set up or anything else changing the particles over time. It's a pretty barebones particle system but I haven't been able to figure out what is going on by searching or looking at the settings.

 

I wonder if this has to do with the colour gradient thing?

 

I figured out a way around the issue. I originally set the texture to the default particle and removing the texture fixed the issue. It also fixed the read/write error in the bottom left.

Will have to see if a custom texture will have similar problems, though.

 

Ah. You set a texture in the Shape section.
https://docs.unity3d.com/Manual/PartSysShapeModule.html

That doesn't change the shape / texture of the particle, it changes the shape the particles are spawned at and the starting color multiplier. If you want to change the texture used by the particle itself you want to use a different material with its texture set to the one you want. Or alternative use a sprite in the Texture Animation section.