Hi there!
I noticed that post #2555458 and its child, post #2559459, are locked to remove the "lynel" tag. The historical post changes #2555458 and post changes #2559459 show that the tag was locked after the conclusion of a small edit war, with the following reason given one year ago:
Cannot infer that this is lynel without the upper body being visible
However, I would like clarification on this. It seems to me that there is sufficient information within the picture to demonstrate that the character penetrating Kass is a lynel, given the distinctive bandages wrapped around the legs, the red hair sprouting out just above the hooves, the long, red-haired tail, and the brown fur overall. Indeed, comparing the character in the animation's brown fur, bandages, red-haired tail, and red hair above its hooves against the lynel's in-game model shows a perfect match in all distinctive features of the species fucking Kass in this animation.
As described in e621:tag what you see (explained),
Therefore, for every post on the site, it can be assumed that e621's tagging system is actually saying "this post appears to contain X" rather than "this post definitely contains X".
There is more than enough information in the animation to demonstrate that it appears to depict a lynel, even if we cannot conclude that it definitely depicts a lynel. It would be more surprising if this turned out not to be a lynel, given the fur colouration pattern, quadrupedal body shape, and bandages all being consistent with the lynel species. In fact, it seems to me that the evidence is overwhelming enough that we are equally well justified in tagging the picture "lynel" as we are applying the tags "horse", "taur", or any of the other species tags attributed to the animation right now.
Updated