Header Image Issues

Hi, For some strange reason, my header image insists on reverting to an image I first used, but have since removed as the header image as well as deleted from media library. However, that image is still being used and I have no idea why. I'm hoping you can help get to the bottom of it. Steps I've taken:

Purged All cache Reset browsing history and cleared cookies/cache Added a new image and set that as both the header image and featured image on my Pages

How can an image that isn't even in my media library still be used? The correct image that should be used across the site is a standalone microphone. The incorrect image is B&W club scene. https://rbfinland.com