Judging based on expectations is always a delicate and tricky matter, but I think it would be pretty understandable to call a 125M opening, a 350 total, or a 700 WW an underperformance. Those would all be very poorly ranked compared to most past Batman movies, which is a decently populous reference class. Such nums are fine for weaker franchises/nonfranchise fare, fine for top tiers franchises in the aughts/early 10s maybe, and fine (more than fine, actually) for a pandemic era release. But covid is really wound down at this point, so...
Edit:Joker comparisons make 0 sense though imo. That movie is an outlier and exception in an extreme sense, not really a Batman movie or an action superhero movie at all. Instead I would look at Bvs, Nolan, and pre Nolan Batman solos -- but especially first entries. Batman 2 will do gangbusters as long as Batman 1 delivers the quality.