Those arms are from tails though because it's chakra.It can't be like that, because this way it wouldn't be incarnated into Naruto since he was born before Minato died.
And Kurama told that Naruto reminds him of someone. It could be Ashura.
There is clear evidence, if you don't see it, oh well... I guess it can't be helped. Moon exlipes do exist regardless of you seing them or not, you know
Cant you see the upper pannel? Tails do not have fingers.
With this scan I only proved that Kurama's bijuu mode is capable of having any amount of arms.
And "should be" is not an argument, it's your assumption.
This on the other hand (lol) are actually arms. That chakra cloak is Ashura's own chakra.
The Sage himself said Ashura's chakra was reincarnated into Naruto.
This means that Naruto's cloak looks like that because of Ashura's chakra, not Ashura's chakra looking like that because of Kurama cloak.
Edit: End of Days already covered it.