As you know, the trail renderer component has a material and a color tab for its color. When i apply the material for the trail, it applies nicely, BUT if i don’t assign a material and try a color, it just stays purple, like when you don’t have a material applied (I need this because i can’t make gradients in materials).
Thanks for all answers 
Everything that is rendered on screen needs a material other than objects with sprite renderers. The pink/purple color is showing you the mesh that is being created to inform you that it doesn’t have a material applied and it needs one in order for it to properly render. Take a look at the docs on color gradients (as you can see, it references the trail renderers “material”):