IME DEI is usually a function rolled into HR (although they often contract with diversity training firms), rather than a separate team, except at large companies. Where there are separate DEI teams, they tend to be the most diverse, at least among the white-collar workforce - the requirements for these jobs tend to be quite nonspecific, because they don't really need to do much besides write stuff and give presentations related to diversity. These tasks can, at a pinch, be mostly handed off to interns and ChatGPT, or else involve cribbing from preexisting presentation templates. The actual engineering, PM, etc., teams tend to be less diverse - graduates of specific university programs tend to be less diverse, in the non-euphemistic sense, than university graduates as a whole.