Warning: SPOILERS for Superman & Lois season 1's premiere,
Superman & Lois is set in the Arrowverse but the series premiere ignores the events of Crisis On Infinite Earths. Starring Tyler Hoechlin as Clark Kent and Elizabeth Tulloch as Lois Lane, Superman & Lois is a new vision of the Man of Steel's adventures: this time, Lois and Clark are parents of two teenage boys who decide to relocate their family to Kent's childhood hometown, Smallville, Kansas. But fans may be left wondering why Superman & Lois doesn't reference the Arrowverse or last year's Crisis.
Tyler Hoechlin's Superman was introduced in Supergirl season 2, and the two Kryptonian cousins originally lived in Earth-38 in the Arrowverse's Multiverse. The Man of Steel met the other superheroes of the Arrowverse in 2018's Elseworlds crossover, but 2019/2020's Crisis On Infinite Earths destroyed and remade the entire Multiverse. By the time Crisis was over, Earth-38 was merged into Earth-1, where Green Arrow (Stephen Amell), The Flash (Grant Gustin), and the other superheroes lived. For Superman, this meant an even more shocking change: He and Lois had just had a baby in Argo City but when the Man of Steel came home from Crisis, he suddenly found out he was the father of twin teenage boys instead. Jonathan (Jordan Elsass) and Jordan Kent (Alex Garfin), naturally, are major characters in Superman & Lois, and the series premiere revealed Jordan is manifesting superpowers like his father.
Superman & Lois doesn't reference Crisis or the greater Arrowverse at all, even though all of the costumed crimefighters share the same planet. Instead, Superman & Lois resets the Man of Steel as the world's protector, who is beloved by millions. This is a bit curious since Supergirl had previously established the global fame and importance of Kara Zor-El (Melissa Benoist), which even Superman acknowledged in her series. There was even a key moment in Superman & Lois' pilot where Lane told her husband his family needed him at home; this would have been the ideal time for Clark Kent to call his cousin Kara and ask her to step in and look into the problem of a mystery villain attacking nuclear reactors he was dealing with. However, Superman & Lois' goal was to have their prime superhero stand apart and establish his preeminence in his own series, which is understandable.
There are a few key reasons why Superman & Lois didn't dip into the wider lore of the Arrowverse: Superman brings his own greater fanbase, many of whom aren't necessarily up to date on the last decade of The CW's intertwined universe but would tune in to see a new show about Superman - especially since the DCEU isn't moving forward with another Man of Steel movie starring Henry Cavill. Leaving the Arrowverse out of the narrative certainly made Superman & Lois more accessible to general audiences and rightly put the focus on Clark, Lois, and their boys without the distraction of Supergirl or other heroes doing flybys in Smallville.
Additionally, the realities of TV production in the COVID-19 era seriously limit Arrowverse's ability to indulge in crossovers like in the past; a planned Batwoman/Superman & Lois event had to be scrapped because of the pandemic. Further, Melissa Benoist was pregnant during the production of Superman & Lois' pilot, which, along with COVID concerns, explains why Supergirl was absent and wasn't even mentioned in her cousin's new show. Supergirl season 6's production was also delayed to accommodate the star's new addition to her family.
Still, it was a bit jarring for diehard Arrowverse fans for Superman & Lois to completely gloss over the events of Crisis On Infinite Earths. Superman & Lois began with Clark narrating his life and he only fleetingly referenced his becoming a father and didn't acknowledge Superman's weird change of ending up as the parent of instant teenage boys. But then again, trying to explain how that happened in Crisis during an opening monologue would have instantly launched Superman & Lois with avoidable confusion. Ultimately, Superman & Lois made the wiser decision to leave the greater Arrowverse on the horizon (for now) and give the Man of Steel and his family the spotlight.