It’s basically old-school gmod animation (I think it might have been done in source filmmaker, but a lot of SFM animators got started with gmod) that somehow got popular with gen-z/gen alpha. Gmod used to be a very common tool for people to make 3d animations with (especially animations revolving around Valve games) because it had access to all of Valve’s models and was extremely moddable. They were almost like 21st-century claymation.
Anyway, gmod and SFM animations have always been surreal and nonsensical. I imagine part of the reason it blew up is because of toilet humor and because it graduated from a dumb toilet-humor animation and into a surreal Kaiju battling series.