You're right, it doesn't make sense. The spell that Peter asked Doctor Strange to perform was supposed to make everyone forget that he was Spider-Man, which Peter corrupted when he kept adding conditions to it, and somehow brought people from other dimensions to his who knew that Peter Parker was Spider-Man. When Peter has Strange do the original spell with no conditions, it returns everyone back to their dimensions. There's no explanation for why Toomes ends up in Morbius' world. It's possible that Toomes was originally from the Morbius universe and was returned there in the spell, meaning he had travelled dimensions prior to the events of Homecoming. There's no explanation for Toomes possessing a Vulture suit in Morbius' dimension, either. Either there's a Vulture in this world already who has the suit and this Toomes stole it, or he immediately began crafting one with no resources in a new dimension. It's so stupid.