Copyright infringement on designs?

[Sephiroth]

I created a toon design called "Ermen Vehn Buran". I been noticing other people using my design as a base for theirs and virtually not changing anything but the color plus a few features such as beards. I am fine with this, but I noticed an actual DJ group is now using my base design for their profile picture. Kheiro & Medi is the group that duplicated my design and changed the color of both. Adding just a few features like beards. So in short I am just wondering if this is enough for potentially enforce copyright laws onto them? Such as if they release a song or merchandise with that design on there. Or if it obviously helps them generate revenues?

I also disclosed a copyright statement in my about section from a few months ago when I created the design.
https://www.facebook.com/ermen.vehnburan

https://www.facebook.com/KheiroandMedi