(1) Kishimoto made it blue once.
(2) The Anime, which he no doubt has influence on, just decides to make it purple? Lol.
Kishimoto has obviously since then allowed it to be purple since it hasn't changed.
There is so much added garbage into the anime that you cant even take it as a credible source.
Kurama breathes fire in the anime & pein can tank boulders with his head...
Madara in the recent 322 was spamming fireballs onto the battlefield, does that mean he can do it canonically? Not in the slightest.
Itachi's susanoo is golden in the manga, sasuke's is blue (hence karin calling it "cold") & as the OP mentioned it also has six fingers, to deny the color of susanoo based on anime depictions means that you accept all of these other "pserdo" facts to be true.
There's a bunch more things in the anime that isnt depicted in the manga, your logic suggests that they are all canon.