I don't think No Way Home (which I assume is what you mean, not Far From Home) is remotely a fair comparision. NWH had way more interest because of the nostalgia factor - right from the start it was evident that some big name from the franchise's past were returning. NWH is a movie that literally brings together three generations of Spider-Man on screen, and their fans.
Not sure where this idea of Batman's star being on the decline is coming from...