I've completed Lostbelt 6 yesterday and want to talk about it somewhere. The weirdest thing about this Lostbelt is how it is being used to promote Nasu's fetishes. There would be obvious spoilers to the LB6 story points.
First, the Artoria and Muramasa storyline, which unravels Nasu's blatant lie. Some years ago Nasu told his fanbase that Saber will never get a storyline in FGO, because "her story is over". He actually followed this modus operandi for some time, and allowed different Artoria versions to be their own character. Now, with Lostbelt 6, he abandoned that ideals to reuse the same weird Fate route inside of different medium and with different characters, which makes it complete joke instead of good story. Muramasa is 70+ year old man, a blacksmith, meanwhile he is being paired with Artoria for no reason in the chapter. You may think it was perfect opportunity to make actual good story with the FGO protagonist and Artoria, who is main character of the chapter, which would make a much more sense and be actually interesting, but instead Nasu pair her with old man and pretends that it is fine. As a result, the fanart is already poisoned by the clappers, who don't even care about actual Muramasa (who had decent characterisation in Shimousa) and Artoria (Fairy). There is no reason for Muramasa to even appear on our side in LB6 (we are enemies of Alien God), he is there as part of our group just because Nasu wants to "remind" the readers of story which has been "ended" long ago (according to his own words).
Second, it is the way that he writes certain female characters (as a female myself, I feel it is important). We don't have proper female villains, Olga is being flanderised, presented as a clown and Servant Universe tier villain (and it's the long awaited Beast of the End, the final Evil of Humanity). It's not even just my opinion, since there are some sites which cites my opinion. Then we have Morgan, who was supposed to be the evil monster of Nasuverse, who abused Artoria, did a bunch of atrocities and Nasu just cancelled her whole character to appeal to people who want to have her summonable (since, no one would really like pan-history Morgan as person/"waifu"). She was flanderised, get a random weird characterisation like being afraid of caterpillars. You can read more there. And this happens to most of female characters, that Nasu writes, notable also Kiara, Koyanskaya.
I feel like LB6 is the end of Nasu's reign and the "cult" which does indeed exists around his works.