If you turn off PubMed Correction and PMID Linking and/or Crossref Correction and DOI Linking, you will see the following warning:
We strongly recommend using both of these checks along with Cabells Reference Checking, because the additional information and validation from the PubMed and Crossref databases allows Edifix to refine the Cabells results, leading to more informative warnings and reducing the likelihood of false positives.