I guess Manga also had an "80s-90s" style considering how many of them started looking like shit after 2013.
You're smoking crack? I thought they were underdetailed and recycled. Demon slayer feels like generic shounen 101 (tanjiro is a pussy), Jujutsu Kaisen feels like a Naruto ripoff, MHA is mid, everything else is isekai out the ass and light novels everywhere or doujins ofc. It's amazing to think the pussy shounen jump of today which publishes crap like kagurabachi and roboco once published one of the most detailed and badass series possible in Fist of the north star or even something like slam dunk.
The degeneration of artistic skill is proportional to the progression in time. It is just simple fact, the causes for it are multifaceted but to deny it happens is just false. This is not just in anime but in manga and everything else as well.
The manga field is so widely immense, at such ridiculous degree, that trying to label its entirety through a very flawed argument (akin to graphic fidelity on the topic of videogames) and weekly shounen titles as primary examples only highlight your inexperience. And we went through that bit already some weeks ago, monthly-issued manga series are largely different in process (and more manageable for artists overall) than their weekly-issued counterparts.
Tsuneko Maruru to Hachi - Sonoda Yuri (2022 - onwards)
Space Battleship Yamato 2199 - Murakawa Michio (2013 - onwards)
Tora wa Ryuu wo Mada Tabenai - Hachi Inaba (2022 - onwards)
The Little Match Girl - Suzuki Sanami ( 2014 - 2018 )
Tsukiyo no Toratsugumi - Kasai Uni (2017)
Shinmai Shimai no Futari Gohan - Hiiragi Yutaka (2015 - onwards)
I could provide a lot more examples although my post would end up being insanely long. But I hope you get the gist.
Also, mangas from "less talented" artists existed plenty in numbers before 2013 too, such as Tekkon Kinkreet (1993, Matsumoto Taiyou) and Medarot (1997, Horuma Rin).
I won't say much about animation itself as I'm someone who focuses far more on comics instead.
But the notion that manga is going through some sort of dark age and talent drain, much like the idea that the field was gatekept by "more talented" artists, is both laugheable and out of touch with the reality.