Hover state for image modal

I am trying to do a class that allows hover image to fade on in the modal for my ‘get reel’ section of my website. When I do it I am changing the background image, does anyone know what I should be affecting. I did a ‘content’ change but that does allow a fade.

The default appears to be a slight fade effect but I want it to have no ‘dimming’ just a fade to the other image I replace the current one with. Cheers!

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