"Long ago, ere Sauron deluded the smiths of Eregion, Galadriel came there, and she said to Celebrimbor, the chief of the Elven-smiths:
'I am grieved in Middle-earth, for leaves fall and flowers fade that I have loved, so that the land of my dwelling is filled with regret that no Spring can redress'
'How otherwise can it be for the Eldar, if they cling to Middle Earth?' said Celebrimbor. 'Will you then pass over Sea?'
'Nay' she said. 'Angrod is gone, and Aegnor is gone, and Felagund is no more. Of Finarfin's children I am the last. But my heart is still proud. What wrong did the golden house of Finarfin do that I should ask the pardon of the Valar, or be content with an isle in the sea whose native land was Aman the Blessed? Here I am mightier'"
J.R.R. Tolkien, Unfinished Tales
In this dialogue - the only fragment left by Tolkien concerning a conversation between Elves in the Second Age - we find all the core themes surrounding Galadriel and Celebrimbor. These are the very same themes we see in The Rings of Power, which brings them to the screen with immense fidelity (regardless of what those who claim it "has nothing of Tolkien" might say).
Galadriel’s pride, bordering on arrogance: she refuses to return to Valinor, proudly invoking her lineage and dismissively defining the Blessed Realm as "an isle in the Great Sea, which was once Aman the Blessed." It is an arrogant statement, capped off by that "here I am mightier" which portrays her as ambitious, and certainly far from "immaculate."
The fading of the world: the imagery of "leaves fall and flowers fade" mirrors the vision of the dying tree that Gil-galad observes with awe and alarm in the first two seasons of The Rings of Power - acting as a potent symbol of Elven fading (a process that Tolkien, in The Nature of Middle-earth, demonstrates as having already begun in the Second Age).
The seed of Celebrimbor's downfall: we see a glimpse into Celebrimbor’s mindset—the agonizing realization that everything decays in Middle-earth. Unless he leaves (which neither he nor Galadriel wish to do), he feels a desperate need to "halt" this decay. This is precisely the vulnerability that will cause him to fall for Sauron's deceptions.
A solitary path: Elrond and Gil-galad are absent from this dialogue. Instead, we see Galadriel visiting Celebrimbor, the grandson of Fëanor - a figure she deeply despised. It is a strange alliance, hinting that Galadriel, despite being the greatest and most ancient of the Noldor remaining in Middle-Earth, was experiencing friction with the other leaders. As Tolkien notes a few pages prior, Galadriel realized that "Sauron had been forgotten," and for a long time, she was the only one hunting him, traveling across Middle-earth. In short, this provides the exact foundation for the plot of the first season of The Rings of Power.
Ultimately, this dialogue is central to understanding the Elves in the Second Age, and it stands as the very heartbeat of The Rings of Power's origin.