1) Shanks doesn't have a left elbow, so I consider it pretty telling that the silhouette has one to begin with
2) On top of this, we're seeing what should be an arm bend, if there wasn't an arm coming from the elbow this would just be impossible.
Unless the theory has suddenly turned into 'Shanks is both secretly evil and has a secret prosthetic arm he's been hiding this whole time' I don't see any explanation for it.
I also don't get people assuming that Oda would just exclude Shanks' scar (solely for two different scenes for the same mysterious cloaked guy, with no other cases of this happening for Shanks normally) for the sake of keeping things hard to predict. This is one of the mysteries in the series that has clues surrounding it ahead of time- what is the point of introducing fake evidence, like not a red herring but intentionally drawing something in a way that's inconsistent with every other time you draw the same thing, when it only ruins readers ability to trust real evidence for mysteries in general going forward? Red herrings in One Piece are more along the lines of Saul also being reintroduced with burn scars after we're already made to speculate about a 'man marked by flames'- this is so we can trust what we're objectively told (Saul was burned, and there's another potentially unrelated man who likely has burn scars) as long as we're critically thinking when making our assumptions, and this way it doesn't ruin the mysteries going forward. Obviously, not everything in One Piece is logical- but the mysteries in the series, and their clues and red herrings, do follow this rule because it allows the readers to continue being invested in mysteries and rumors going forward, whether they're right about the current one or not.
Also, there's the blatant issue of Oda including Shanks and this mystery saber-wielding guy (who is using his left arm lol) as two different people in the 'it all depends on who find the One Piece!' spread page.
In total, you have to assume all the evidence we've been given so far is entirely there to deceive us and has zero value towards solving an actual mystery, and the 500 IQ galaxy brain play is to actually ignore everything we've been given and say 'is Shanks secretly evil?' even though we've seen his internal monologue before lol. This is ZKK type nonsense
