Kurama noticed early that Sasuke stole the chakra, so he stopped feeding Naruto with it.
Once Sasuke let go of Naruto, Kurama channeled some more chakra to Naruto.
Naruto goes down hon he's knees and hide the chakra as chakra arms under the water (Hence why Sasuke can't see the chakra with his sharingan looking at Naruto and not under his feed.
Naruto will obviously pull his feets away or forming a chakra clone behind Sasuke or something like that.
Once Sasuke let go of Naruto, Kurama channeled some more chakra to Naruto.
Naruto goes down hon he's knees and hide the chakra as chakra arms under the water (Hence why Sasuke can't see the chakra with his sharingan looking at Naruto and not under his feed.
Naruto will obviously pull his feets away or forming a chakra clone behind Sasuke or something like that.