I've been on the multiverse idea from a philosophical point of view for a while. For me it's a perspective thing. Our observable universe has a hard limit. Due to expansion anything already out side that bubble will never be apart of it. In that sense there are at least 2 universes the one I am in can see and everything else that i can not. If another being was in another part of space say 50 billion light. Years away, our 2 observable universes could have different localized rules of physics and be fundamentally different.

But then also there is the possibility of overspace as well. In the sense that physics breaks down at the quantum level behaving in ways that are impossible on the macro level. The possibility of an overspace leaves the door open on the multiverse. But who knows