AlbertoJohnAvil
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The punch wasn't multiversal, because Earth wasn't damaged beyond continent level damage. Heck, IIRC the feat of him jumping off the planet earlier showed more destruction.
Secondly, did you read the issue? The World Forger is forging a "crisis anvil" to replace the prime earth with his Earth so that the "plan" to stop Perpetua will work. Blue energy is coming off of him and going into the anvil. Every other time, that I can recall, that a monitor exuded energy from themselves into something else they got slightly weaker. And finally, even if he's not weaker, we've seen that the Monitor's durability (outside fully powered up Anti-Monitor at the end of CoIE) is not always the best. Mandrakk II could get staked by a lantern construct, Nix could get punched by a bunch of Flashes, Mandrakk I after coming back into the story was able to be beat by the guys from The Unexpected. Monitors explicitly only exist because of the corruption they got from narratives. Now, currently that narrative includes being Perpetua's "children," but it's still a narrative they are bound to. They can't escape narrative logic, that's literally what they are, a narrative given form.
Regardless of all that, the World Forger has no multiversal durability feats, at all. Barbatos killed him, and he reformed in the 6th Dimension. That's all we know about his durability until this fight right now. He has no multiversal durability because he's not been attacked by an attack that is shown to be able to destroy multiple universes at once. Given that the 6th dimension is explicitly a realm "Beyond imagination. Beyond understanding.", physics aren't exactly going to be the same there as in the normal multiverse either. We know that the realm of Imagination has all kinds of wonky physics, the 6th dimension being beyond that and being wonky makes sense too.