It sounds like both sites have a serious, unchecked favoritism problem.
@Brenda Swatek as Executive VP of HR overseeing these sites, how about stepping in and addressing these issues? At the very least, take meaningful steps to rein them in. The situation has gotten way out of control, and employee surveys over the past several years have highlighted these concerns unambiguously.
At what point does leadership take accountability and act on the feedback employees have been providing for years? You know what’s going on, and the evidence is there. It’s time to stop turning a blind eye and start holding people accountable. Just follow the literal guidelines in our own training on these topics, verbatim, and apply them consistently.