Any movie that delves into something as chaotic as the multiverse is going to suffer a lot of problems.
1) You can't invest in any character, because they're all disposable.
2) The story arcs into a million threads you can't follow
3) The visuals try to compensate for your lack of understanding of the multiverse (hopelessly, despite the budget)
4) Lack of coherence
5) Visual and audio noise that never stops to take stock and re-evaluate the situation
I'd say, if anyone wants to try their hand again at a multiverse theme, either do a shallow dive in a movie (you only have about 90 minutes to do it), or create a series that explores it one chunk at a time that your audience can actually understand, and allows you to create characters we actually care about.