As the others here are implying, the current consensus in the Physics community is that the many worlds hypothesis is not falsifiable, and so should be disregarded in favor of funding theories that can be proven or disproven. String theorists, the biggest proponents of the many worlds theory, are generally ostracized from greater physics academia since they have failed to produce any experimental designs to validate their claims for several decades after taking up a lot of tenured positions in the 90’s, along with the “pop science” PR campaigning for their position that started then with some popular books and continues to this day in the works of Michio Kaku for example.

Relevant panels by leading physicists here: https://youtu.be/CNjckutR7BE?si=t88BigaInz01zamL and here: https://youtu.be/eOvqJwgY8ow?si=5pbtgQqByJfi0Opi

Scientifically, we cannot yet talk about theories that are untestable and unfalsifiable. Sure, math or some other theory may imply other dimensions or parellel universes, but how will you measure one?