Your colors contrast too much, making it look like a cake. Your shadows are harsh and gradient rather than flat, and they do not use the material shading guideline. Your lighting angle is different.

"Any designer can find [my] mistake if they spend some time looking at the design." Tell us what you did wrong rather than puffing your feathers

If I write "O" and draw a circle around it, I didn't steal your design. Only they know if they used your design as a model or not. I'm sorry, but I don't buy your theory. I think it's moreso inspired by the letter O and Material Design.