At their core (and as far as I understand), LLMs are based on pre-existing texts, and use statistical algorithms to stitch together text that is consistent with these.
An original research manuscript will not have formed part of any LLMs training dataset, so there is no conceivable way that it can evaluate it, regardless of claims that LLMs "understand" anything or not.
Reviewers who use LLMs are likely deluding themselves that they are now more productive due to use of AI, when in fact they are just polluting science through their own ignorance of epistemology.