The WHO report clearly states:

“We did not consider the hypothesis of deliberate release or deliberate bioengineering of SARS-CoV-2 for release, the latter has been ruled out by other scientists following analyses of the genome (3).”

The single Nature article they cite argues irrationally about the subject:

“However, since we observed all notable SARS-CoV-2 features, including the optimized RBD and polybasic cleavage site, in related coronaviruses in nature, we do not believe that any type of laboratory-based scenario is plausible.“

Since similar traits were found in various other viruses, no one could have combined them in a lab. Actually, their existence in nature in separate virus strains increases the likelihood that they were engineered into one that combines selected traits from other viruses. It also does not prove that these other specimens did not have a lab origin before being discovered. Most crucially, it says absolutely nothing about the virus manipulation methods known to exist in these laboratories.