It's amazing how many people just accept that claim, despite it being missing the "because…" and just accept that it discredits the document.
I guess they've backed off of it a little, because of the sheer absurdity, but the real claim isn't just that it was plagiarized from Dialogue in Hell but that the supposed forgers pieced it together from dozens of other works, for no discernible reason, in a needlessly complicated operation. Obviously, if you break something down into small enough bits, you can find similar ideas in other texts.
The only works that it bears enough of a resemblance to that we can say with certainty that its authors had read them are Dialogue in Hell - a popular book at the time, contrary to what people say - and Herzl's Der Judenstaat, which any zionist thinkers would be familiar with. Those similarities only account for around 1/5 of the text, with the rest of it being original.
That being said, all of the modern editions come from the adulterated one published by Nilus, meaning they aren't completely true to the original. He both added and removed material, most notably, he absorbed an editor's note about Nietzsche and Darwin into The Protocols itself, which is often harped upon by deboonkers. He also omitted quotes form the Torah.
The best material on The Protocols comes from Karl Radl. The pdf is his entire series of articles on it, and you can also hear the shows he did with Deanna Spingola on the subject here: https://www.bitchute.com/video/VCWTlF74B9ZC/
