Board Thread:Episode Discussions/@comment-25319479-20180719110008/@comment-30643398-20180721183254

SPSM is pretty much an upgraded version of the regular Sage Mode, which he can use in conjunction with his chakra cloaks.

Because of the fact that he no longer looks like he did when fighting TTJ Madara/Kaguya, people speculate he is only drawing on the power of Kurama, i.e. Nine-Tail's Chakra Mode instead of all Nine-Tailed Beasts.

If this is true, Naruto still has one higher form he has not shown as an adult.