You have read your own sources, right?

The first one, from marxists.org is an article about the Germans and why they let the Nazis seize power. The The author attests that

And the German people, intoxicated by demagoguery, driven by the scourges of terror, with barbarously perverted instincts, wandered towards death.

And uses The Magic Mountain and Heinrich Mann’s novel The Loyal Subject as examples for the then current condition of Germany. At no point does it mention anything anti-fascist about either book by the way.
It tells us that Mann identified mental conditions, the dissatisfaction, moral disgust, inability to understand why.
These are themes the reviewer identifies in the book.

That the people thus affected are ripe to accept fascism, later when it eventually comes about, is the reviewers conclusion.
It is not something expressed in the book.

Further down, other works are discussed and they are specifically called “anti-fascist” unlike The Magic Mountain.
About Farewell by Johannes Becher it says:

Although the action of this novel, like the action of The Magic Mountain, is played out before the first world imperialist war, it is inspired by the modern anti-fascist struggle.

It draws the parallel of both books being set before WWI and the distinction that only one of them is is inspired by the modern anti-fascist struggle. It is not Mann’s.

Your second quote mentions The Magic Mountain in the first line and is then entirely about The Cabinet of Dr. Caligari.

And the third one

he became such a forceful foe of Nazism

Yes, we’ve been over this. He didn’t like them from the beginning. Certainly didn’t improve his opinion when they set up their fascist regime, years after 1924.
All the same arguments about the passage of time and when things happen, that I’ve made before.

and the author’s experiences

You have to be joking.
I have constantly pointed out that Mann had not yet experienced fascism. That would happen later.

As I said it’s been a long time, so let’s see what we find for analysis on Naphta:

Naphta is termed a “revolutionary” and “socialist”, but Settembrini sees Naphta’s fantasies as emanating from an anti-humanitarian reactionary revolution […]
The association here between Naphta’s advocacy of terrorism and two extremely conservative movements – Prussian militarism and Jesuitism – is a huge political shift for the novel.

Yes, revolution and militarism, well known concepts at the time, unlike fascism.
Almost like references to the forces that embattled the Weimar Republic at the time, the socialists who wanted to join the world revolution and the military who wanted to re-start the war they claimed to have lost only because of the cowardly politicians.
Funny how that fits together when you consider the actual time it was written instead of the 30s or the cold war.

Ah, and here is a review that explicitly covers authoritarian nationalism:

he wrote and delivered his speech, On the German Republic.
In it, he publicly embraced the postwar Weimar Republic and the principles of its democracy, distancing himself from the types of authoritarian nationalism […]
By the time he finished writing, the work had been transformed from a satirical novella into a sweeping Bildungsroman, focused on moral education and psychological development. It was now also an allegory of European civilisation teetering on the abyss – a “world festival of death”, as Mann puts it in the novel’s final sentence. […]
Specifically, the phrase is a reference to World War I. More broadly – and just as powerfully – it reflects the sense of postwar disillusionment and social malaise that shaped the novel.

Authoritarian nationalism is certainly also an element of fascism but not exclusive to it.
It has been prominent in the German Empire before WWI and indeed this review draws the direct link to the war, which is something that Mann knows about and can react to unlike the rise of fascism which happens later.

Your desire to bifurcate periods of time and development of ideologies into artificial divisions is childish.

Sorry, I live in a world of linear time where later events and ideas cannot influence the past.

What i find more childish is your stubborn insistence on a point that you simultaneously refuse to prove.
It’s funny how you claim to be handing me things when all you’ve done is quote unrelated third hand accounts of Mann’s life and nothing from the book. Not even a literary analysis that supports your claim.
All while completely ignoring that I’ve repeatedly shown you ways how you could make your case.

I agree that this was big waste of time, lets agree to not do it again.

So, did Mann know what Adolf would write in his book or what the Nazis would do in the 30s and 40s?
Did he know what Mussolini would get up to in the next decades?

No? Then he couldn’t have reacted to that. So none of that can be relevant to what he had written in 1924.

Now, it’s not unheard of that authors can see the proverbial writing on the wall and anticipate future events to some degree. But to argue that you would also have to actually point to his writing and draw parallels. You can’t just point at later events as proof for what is in the book.

Are you claiming The Magic Mountain is a reaction to Mein Kampf, a book that had not been published by then?

Naptha is clearly a fascist in all but name

Now, this is actually an argument engaging with the material.
It’s been ages since I read the book, can you remind me what Naphtha says and does and how the book critically engages with that.

Yes I read it.
It has not a single reference to fascism in the 1920s.

The Weimar Republic was embattled primarily by monarchists and socialists/ communists; the NSDAP had not yet risen to power and not established fascism in Germany.
The Dachau concentration camp was opened in 1933, a decade after the book was published.

Again, you have not talked about anything actually in the book that relates to fascism.

your understanding of history must be so mutilated

I beg you to open a history book and look up when the rise of fascism happened.
In 1924 the NSDAP was a bunch of violent thugs pretending to be socialists. Their rise to power happened a decade later. The only fascist was Mussolini and he had not yet fully implemented all that we nowadays call fascism.

You have not made one single argument that actually ties anything in the book to fascism.
You keep quoting articles about Mann’s later life but the only reference you made to the book itself was mentioning the eve of WWI which at least time-wise sets the action before the rise of fascism.

You have not identified one anti-fascist theme in the book nor quoted any literary analysis that does so.

If you desperately want to make this argument, then you have to ask yourself:
What is fascism? What are its defining characteristics? Where does the book address them?
And which themes are specific to fascism? Contemplating mortality as such is not.

Read The Color Purple or Their Eyes Were Watching God

Do they contain sociological studies that support your claim that

Germany has a special relationship with "whiteness”

Otherwise I don’t see what you think this is adding to the conversation.

As for The Magic Mountain:

its perspective from the eve of WW1 mirrors our current position

We currently don’t have European empires in a mutual standoff waiting for the powder-keg to be lit. By all accounts most people are more reminded of the inter-war period with the rising fascism.

The Magic Mountain is easily one of the most important novels of the 20th century

I never disagreed but being important does not automatically make it anti-fascist.

In 1933, when Hitler came to power, Mann moved his own family to Switzerland

And just like his cold war experiences that you quoted before, this happened after he published Zauberberg in 1924.
At the time, Mussolini’s regime had barely begun and Hitler was a failed putschist in jail.

Come up with a better argument if you want to cut me down.

Dude, your only “arguments” are wikipedia quotes about Mann’s life after he published the book, completely unrelated literature recommendations and an unexplained association of fascism with the eve of WWI.

I think Germany has a special relationship with “whiteness”

No that’s the US. Racism in Germany and Europe as a whole, has always been about cultural and ethnic differences more than skin color. The persecuted slavs or jews were just as pasty as any German, unlike the “honorary Aryans” in Japan.

Germany is a culture bursting with contradictions, within a year of Mein Kempf being published another novel was published The Magic Mountain by Thomas Mann

Two different authors with different backgrounds writing different books? What a uniquely contradictory culture Germany is.
Disregard that one of them is lauded for its literary and cultural significance while the other is basically as important as the art of the deal.

And of course the explanation for contemporary German culture and its problematic relation to Israel can be found in the literature of 1924.
Nothing significant happened since then, right? Everyone was on vacation in the 30s and 40s. Occupation, the Cold War, the literal formation of the country of Israel? Surely none of the could have any relevance.

I do agree that the Magic Mountain is a great book.
But although some of its themes do go against aspects of fascism, calling it "the most supremely antifascist novel imaginable " seems a bit of a stretch.