it's clearly all in your head. 4.6 is just as capable as it used to be. literally no one on the internet has managed to post credulous and real evidence of a nerf
this is just another trendy conspiracy theory that people reinforce because of selection/recency bias. you hear "nerf", your brain overindexes on the next time Claude does poorly. it is the same phenomenon when you notice a new vocabulary word all the time.
