TheNemesis2445 said:

What if the artist tagged it at the source?

Hm… let's see. Ah, here we go: https://e621.net/wiki/show?title=tag_what_you_see

Okay, that's the "tag what you see" rules, so let's pick out the important part…

"You may use an OFFICIAL external source of information (the artist, commissioner, or character owner's gallery/website) when tagging a character name ONLY under the following conditions:

1) The external source of information is the artist, commissioner, or character owner's own words on their own gallery or website.

2) The post must have at least SOME evidence of the claimed character and can not have any evidence that CONFLICTS with what the external source is saying (e.g. a post can't be tagged "Character A" just because the external source says so, when the post does not actually contain any evidence of "Character A", or in fact looks more like "Character B" instead.) Again, there must be at least SOME evidence that the character is who it's claimed to be, but it does not have to be definitive proof."

Okay, so by that second rule there, I don't think we could call it Sombra, even if the artist's page says so. There has to be some kind of identifying feature in this singular picture itself, independent of other pictures, and right now all it has a non-specific pony dick. Again, if it were in color, or we could see part of Sombra's cape, then I'd say give it a shot, but right now I don't think we can tag him in it. Also, if you've got a few minutes to spare, checking out the full "tag what you see" page, along with twys for the explanation, might not be a bad idea, just to avoid future confusion.