Is there still no basis for the multiverse theory?

The multiverse theory is acknowledged by many people even without a complete basis, but since it is just a theory, there is no clear basis yet. But scientists are continuing to research it, so who knows? In general, the multiverse theory suggests that there are other universes in the external universe. Based on the assumption that the majority of wire scientists adopt this idea, you may think that this kind of imagination is a reasonable extension of the physics we currently know, but the basis has not been completely proven yet.