Hi Michael, interesting to see a posting of a subject we often see in our daily lives, but something rarely photographed.
Jon can give you much better tech advice re flash etc, but I wonder if you had less flash would it help darken the busy BKG and create better focus on the subject? Overall you could bring thing up in terms of exposure, but for me, its the excessive noise I see in the image, was it under exposed originally? At ISO400 the IQ should be perfect, I've shot the R5 above ISO32k and providing the exposure is good, NR is a breeze. Just a thought, but have you considered a 16x10, cropping a lot off the top, might help tighten the whole framing?
No idea on how you output your hi res Tiff for web, but I see the original post isn't carrying an sRGB profile which it needs to be for web presentation.
TFS
Steve