I think it is Rey’s dramatic pause kind of adds to the cheesiness of the moment. “And I… I’m all the the Jedi.”
I also think simply, “I am a Jedi” would be better than saying she’s all the Jedi.
I think, for me, another good option would be to just cut those last two lines. Palpatine’s final words could be, “A scavenger girl is no match for the power in me!”
And then Rey uses his own power against him, without making some cliché declaration.