As stated by Ethan Siegel, it sounds like nonsense:
We have overwhelming evidence for the hot Big Bang, and also that the Big Bang began with a set of conditions that don’t come with a de facto explanation. If we add in an explanation for it — cosmic inflation — then that inflating spacetime that set up and gave rise to the Big Bang makes its own set of novel predictions. Many of those predictions are borne out by observation, but other predictions also arise as consequences of inflation. One of them is the existence of a myriad of Universes, of disconnected regions each with their own hot Big Bang, that comprise what we know as a multiverse when you take them all together. This doesn’t mean that different Universes have different rules or laws or fundamental constants, or that all the possible quantum outcomes you can imagine occur in some other pocket of the multiverse. It doesn’t even mean that the multiverse is real, as this is a prediction we cannot verify, validate, or falsify. But if the theory of inflation is a good one, and the data says it is, a multiverse is all but inevitable. You may not like it, and you really may not like how some physicists abuse the idea, but until a better, viable alternative to inflation comes around, the multiverse is very much here to stay. Now, at least, you understand why.Ethan Siegel , “This is why physicists suspect the Multiverse very likely exists” at Big Think (December 30, 2021)
But Siegel makes it sound like physics, which is certainly a feat.