>>528737319
The screen goes black during the slashes, like how the screen fades to black when Kris closes their eyes.
When the Knight slashes Tenna, the slashes are black/red (like attack animations you see with the Black Shard equipped) rather than white.
When the Knight does its final attack, if the SOUL is on the left side, it's always moved over to the right side of the screen slash directly across from Kris, implying some kind of separation of the SOUL from Kris. (Although we can still use the menu afterwards, which you can put on the against side.)

>>527653612
That's (You) locking the fuck in. Kris only kneels because the Knight yoinks your Soul away (the heart is always placed to the right and "dragged away" towards the knight see pic related) in their final attack allowing Kris to act however he wants. (you do still control the UI during that, but that's in line with choosing dialogue in chapter 1, 2 and weird route 4 where you still access the UI without being in Kris)

>>527116607
Some people here think that. I don't know if all anons see it that way though. But Kris is pretty clearly working with the Knight so I'm personally inclined to agree. You can also see the Knight teleport the SOUL away in their big attack just before that happens, which is sus as hell and otherwise unexplained.