It's more prominent as a subgenre than it was in the '80s and before, but there are a couple of things worth noting:
1) The default for fantasy was a lot darker back then. Fantasy, on average, has got lighter since the 1980s and earlier. Especially if you're looking at novels, TV and movies. Bridge to Terabithia isn't "dark fantasy", for example, no matter how upsetting it is.
2) All the stuff you list is the exception, not the rule, and you're listing stuff that's wildly successful next to stuff that's a moderate niche success, and stuff that's slightly dark - i.e. has some bad things happen - but isn't really darker than "normal" fantasy in the '80s, like Harry Potter - next to stuff that's nearly pitch black, like Berserk or the more downer zombie stuff.
My whole point is kind of that mainstream media now heavily includes dark fantasy in ways that used to be very niche. In the 80s, comic books, D&D, and fantasy in general were all niche. You could pick up The Dark Knight Returns or Watchmen in comics and it was refreshingly dark, or you could see Superman, Back to the Future, Indiana Jones, Batman '89, Star Trek: TNG, and they were campy or optimistic. Often both! If you wanted something dark, you had to seek it out. It was usually something in the horror genre, which was often campy itself.
Nothing is really campy at the moment. Comedies are not that popular unless they're animated. Comics are still largely dark, and a lot of fantasy novels are dark. But now TV and movies and video games are often dark, too! And not just the horror genre, either. Hell, even Star Trek is dark!
If you don't see it, I'm happy for you, but your disagreement doesn't really alter the root of my perceptions. It doesn't mean I'm any more interested in the stories that modern speculative fiction is trying to tell. It still feels too uniform to me to draw my interest. So when something specifically tries to aim for dark fantasy like D4, it doesn't excite me like it used to.
Like anti-heroes in the 90s, dark fantasy and dystopian elements just feel pretty boring right now. It makes me care less about whatever it is, while historically it drew me in. Noir and hard boiled are two of my favorite genres. Red Harvest is one of my top 2 favorite novels. Nope. Not interested right now.
And "the more recent Marvel movies"? No. Absolutely not. Of those only Multiverse of Madness could even arguably be considered dark, and I'd say that was balanced by the extremely light-side No Way Home (i.e. where MCU Peter Parker finally finds his real compassion and moral center, and where all the bad guys get sent home healed*, not murdered). Wakanda isn't dark, given the ending(s). Thor 4 wasn't dark - a character dying doesn't make a film "dark fantasy", for god's sake. Quantumania is, I presume, not dark - certainly no-one I know who has seen it has suggested it was - the main comparator has been Star Wars.
Sorry, that's my fault for poor phrasing. Recent meaning Phase 2-3. I haven't really been to a cinema since before the pandemic as the one close to me is now gone. I've seen a few post-Infiinty War films, partially because I wasn't interested in the story anymore. If it's less dark that's good, but I don't really care as my interest is already gone. As you can guess, it's been gone for awhile.
This is all on you, frankly.
Yes, my experiences and perceptions are on me. Whose should I be talking about?
Mentioning Hunger Games in the same breath as The First Law or GoT or even The Walking Dead is absolutely nonsense and illustrates a serious failure to engage with the themes and ideas of the works, and instead a focus on entirely superficial elements.
No, it merely indicates that I didn't watch past the first movie. I punched out early. I wasn't really interested in the premise as soon as I understood it, and while I did finish it, I don't really think the first film has particularly well-defined themes. The only solid theme I recall from the first one is "big tyrannical governments are bad." In retrospect, I should've guessed that's what it was going to be from the title, but I didn't really think about it before starting it since I got the movie for free on YouTube on a lark. Either way, I wasn't really interested in a YA Battle Royale, especially one that was 5(?) movies long.
Further, I reject the idea that disliking elements of the setting or plot means you don't
understand the theme. One can understand the themes and still not wish to engage with the topics in the plot, the setting, or the premise. One can understand the themes and still be put off by other elements even if they are as broad and nebulous as "dystopian and dark fantasy tropes." After all, we can say that the theme of most published Dark Sun adventures is heroes surviving and overcoming the odds in the face of ubiquitous and pervasive evil -- quite hopeful! -- and still not be interested in playing the campaign setting simply because we don't want to deal with specific trappings of the setting itself.