With my “rights” antenna up (because my friend’s work was stolen), I used Google’s Reverse Image Search to see if any of my work is being used without permission.
Firstly, I can vouch that Google’s Reverse Image Search works because it quickly found one of my images that is being used permission. (Click the camera icon in the Image search bar and it will ask you the URL of an image to search for. It will search the entire internet for duplicates of that image.)
Next, I was dismayed to find this site which is using one of my images without permission.
I have issued a Take Down Notice. If you have any Africa images on Redbubble then it might be an idea to check if they are also using yours.