I think White Sands Wonder was "Whiter" than intended here, lol.
So I noticed this issue and tested all the Fitting Room backgrounds, and I had these ones show up as white as well:
3rd Anniversary
Monte Fitz Roy
Stormy Cornfields
...
I do notice a white background happens on all of them for a short moment when initialized, but then the background appears on the ones that work.
When I inspect and go to the network tab I also see that the images for the ones not showing are Error 404 Not Found.
https://assets.beta.horsereality.com/c/backgrounds/images/profilebg_3year.jpeg
https://assets.beta.horsereality.com/c/backgrounds/images/profilebg_white_sands_wonder.jpg
https://assets.beta.horsereality.com/c/backgrounds/images/profilebg_stormycornfields.jpg
Also noticed the prod-public-config is different from the beta-public-config and I see that those three aren't in the beta one. Idk if it's related.