Just looked them up.
Fentanyl I found classified as Hardcore Punk, which would already be around since the 80s.
But 100 gecs seems to be something called Hyperpop, which is a genuine new GenZ thing!
Sounds interesting, will have a look!
Calling Femtanyl “hardcore punk” is certainly a choice. Hardcore punk has specific genre conventions (e.g. having drums and guitars) that Femtanyl doesn’t follow at all.