Upekkha means Equanimous-observation , not equanimity! MN 137 is one the the clearest suttas in describing what upekkha does in the four jhānas and samādhi in general. Did it ever boggle your mind how "equanimity" (how almost everyone translates upekkha) is the 7th of 7 awakening factors, but how can a passive attitude of equanimity lead to actual full enlightenment? It can't. People just haven't been translating upekkha properly. It would be like everyone calling a peanut-butter-and-jelly sandwich just "Jelly sandwich". You can't equate the two. Equanimity is sweet, but Peanut-butter, the valuable proteins and fatty acids you need to do vipassana, are where the bulk of the value lies. Upekkha = equanimous-observation that leads to nirvana. Equanimity only leads to rebirth as a peaceful and virtuous Brahma realm god. Upekkha does vipassana. upekkha = upa + ikkhati = looking upon [with right view in 4NT context] Upekkha = right view / wisdom faculty ...
always question authority