Do physicists take the multiverse idea seriously? Specifically, the one in the article that says that there are multiple universes each with different physical laws? (This is very different from QM many worlds, where universes share the same laws.)
Cosmologists interested in fine-tuning might.
Quantum foundation theorists often consider alternatives, not because they think they are real, but because it's useful to understand why QM has the form it does. Mostly their results suggest QM is difficult to modify without becoming trivial or useless.
I think the drive comes more from the metaphysical direction. It's hard to imagine why one set of laws would emerge as physical unless all sets of laws are physical, just by virtue of existing mathematically.
[1] https://www.amazon.com/Our-Mathematical-Universe-Ultimate-Re...
Max Tegmark is famous for his occasional crackpot theories. If anything they make for good sci-fi.
It would be a mistake to call back into question the existence of multiverse. And a mistake as big to claim it exist.
Until a method to test it is found, discussing this idea is a waste of time. However I would respect people searching and discussing methods to test it if they have pertinent things to say.