It was actually “You underestimate my odds” which is a combination of Anakin/Vader and Han Solo. The reason it’s gone is because its corresponding shot doesn’t work anymore. Kylo doesn’t have his hood on, so I tried only using the part where the camera is panned down far enough to ignore that, but then I noticed that he’s got both of his hands on his lightsaber. His new first attack against Vader isn’t an overhead strike, it’s a single-handed swipe from his left.

So, TL;DR, it’s another continuity issue. I can check the fan film to see if there’s another shot of Kylo I can use, but I don’t believe there was one. The substitute here is Vader saying “You are no Sith” to Kylo performing 2 banned ligthsaber moves, and then Kylo says “I know” like Han. Kylo already emulates his father’s finger point thing later on, so it’s clear his dad is top of mind. As he says in TLJ, he never hated him, he only killed him because he thought he HAD to choose power because of fate. This movie clarifies that through the vision of the throne. Plus, Luke says “He would bring… the end of all I loved because of what he would become”.