No, I did not. A theory may have includes the idea that the multiverse caused whatever it predicted, but that is not based on anything except the authors fantasy. It is exactly the same as arbitrarily saying god caused something in a theory, an unobserved event we can say has whatever impact on this universe we want without any proof.

edit let's use a concrete example. This thread is about the cosmological constant. I could easily say that concept is causes by multiverse influence on this universe, just as rightly I could say it's god's finger on the scales. Neither now have experimental data because I can say that.

further edit sorry, this is a bit stuck in my head. Look here

https://en.wikipedia.org/wiki/Multiverse

Notice that it is labeled a hypothesis, and the theories that involve evidence predict a multiverse may be possible with these conditions.