Is there really any problem with an infinate regresion of universes?

[Anomalocaris]

Yes, it is.   Neither theory nor observation insist the supposedly parallel propositions as you put it must be really independent of each other.   All that is required by the fact that our universe appears to be headed towards an end state very different from its initial state is each successive proposition is not required to actually be made from the end state of another.

And so it's not an infinite regression. You're just trying to have your cake and eat it too, i.e. propose some sort of multiverse and try to dress it up as an infinite regression.

And define why it is not?

Either each instantiation itself, or the detaileds of each instantiation, is made possible by a prior instantiation, which in turn depends upon yet another, going back along an infinite chain.  How is that not infinite regression?

 You just can't admit you didn't, or more likely won't, see how infinite regression - not necessarily true but already too threatening to the canard cited to justify the need for theistic creation bullshit - can be embedded in different flavor a of cosmologies consistent with observation.