Seems all mounts are using the wide riding stance off and on for some reason:
Unironically just delete this animation. It glitches onto the wrong mounts all the time. I’d rather my legs clip on big mounts.
Came here to post the same thing. Looks super silly on my bike.
https://i.imgur.com/PJWVpQ3.png
It also seems to be applying this animation to all mounts, even ones that usually have unique animations, like the expedition yak:
It seems to only start after I’ve mounted up on a dragonriding mount.
Feels like someone’s trolling with the MountExtraWide animations at this point. The most hated character animations ever added to WoW being applied to every single mount.
That said, I really don’t know why they thought it was necessary to have the excessively wide leg spread on most races for MountExtraWide. Hopefully this bug is a sign that MountExtraWide is getting changes made to it or something, like getting rid of the ridiculous leg spread.
I am having the same problem.
Looks real bad on flying disc mounts and motorcycles.
I think that prize would go to the new backpedal animations added at Shadowlands launch that were so hated they got removed in like a day. But yeah, the extra wide mount animation is a close second.
So glad it’s not just me with this bug! Seems to have happened upon random to people ever since 10.1 launched. All my characters look like what you showed in the image, but I also noticed this bug hasn’t affected other players I’ve seen roving around.
Hope it gets fixed soon, looks super ridiculous on ottuk mounts particularly!
Still getting this issue. Still very annoying.
Still occurring.
Having the same issue as well.
I did some experimenting and found out it’s the dragonriding mounts! If you log-on on a non-dragonriding mount, the animation will be normal. It can be temporarily fixed by relogging but considering how much we use dragonriding mounts… Doesn’t really matter >.>
edit: it’s most egregious if you use the protodrake
Same.
Bumparoo
Still happening.
Still getting this. 
Can confirm that this bug is still occuring. Hopefully it gets fixed during tomorrow’s maintenance.
Seems mostly fixed, although I am still getting the animation on the Cliffside Wylderdrake.