Curious about Horse Pictures

[Xarias]

I've noticed since I've started playing that some horses, often older ones, have a smokey swirl around them. I was just wondering if this signified anything that I'm not aware of. Thank you so much in advance!

[Naito]

What I found out about this is that the pictures are smoky in Mozilla, but not smoky in Chrome or Microsoft Edge. I don't know the reason behind it though. Before finding this out I thought that horses become dirty over time xD

[Tom]

It's a bug in Firefox.

[Xarias]

Wonderful~ Thank you so much!