Mirrors are a common feature in any play space. They’re a great way to create interesting visuals when the domme is working behind the submissive. In this particular case there’s the additional element of the photographer and the viewer. It’s a very clever composition, creating a sense of chemistry and engagement between the participants while also letting the viewer see that dynamic in multiple ways.
I don’t have a 100% attribution for this. However, based on the content and composition, I’m pretty sure it’s from the StrapOn Dreamer site.