Minato had marked Obito 17years ago , and the marking never disappears, so he used that marking !!! i'm surprised that nobody knew in this thread except "Sakuto" . !!
They actually confused and not because they not knowing about it,
OK from manga fact to manga fact
We all know that FTG mark never disappeared. But manga shown that Minato FTG mark is disappear when Obito turn to Jin and he gain new body.
And after the final fight Obito is back to normal body state because he didn't have any Juubi inside of him.
But the question is, is Obito body is still in his new body or back to his old body.
Where's in the manga stated that obito getting his old body with Minato FTG mark not the Tobirama one?
Here is the confusing part, yes when you thinking about Obito turning back to his old body sure he gain back Minato FTG mark, but where is the manga proof.
That mean many here assume that Obito is still in his new body with Tobirama FTG mark, because that is the closet fact we can get here.