4 Arrowverse heroes who definitely won't be back in Superman and Lois season 4
Batwoman
Superman and Lois might have divorced itself from the Arrowverse after most of the DC TV shows came to unexpected ends, but that wasn't always going to be the case. The show was originally set to cross over with Batwoman in its first season, which made sense at the time given that they were both the new Arrowverse shows (and the Bat-Family's relationship with the Supers in the comics). It didn't happen because of the pandemic and the cancellation of Batwoman essentially made that impossible, especially after Superman and Lois confirmed it was set on another Earth.
It would be pretty full-circle if the show managed to make that Batwoman crossover work before it bowed out. Javicia Leslie brought the Scarlet Knight on over to The Flash during its final season even though her series was no longer on the air, so it would be doable again. The thing that makes it unlikely, however, is that Leslie is now part of the cast for new ABC series High Potential, which is set for a late 2024 premiere on the network. With that in mind, filming could commence in the near-future, so it might not even be possible for her to film a crossover if they planned on doing one.
But honestly, it's highly unlikely that there will be one. Now that Superman and Lois is set on an alternate earth with no other superheroes outside of his son and the Steels, the show just wouldn't have the time to dive into an arc about the multiverse in its final season (not-to-mention the fact that a human hero like a member of the Bat-Family landing on a different earth would be much harder to explain than, say, a speedster).
In another world, we might have gotten that Superman and Lois and Batwoman crossover, but it doesn't look it will happen.