You're applying two completely different standards depending on whether it's Meghan or William.
You accepted the allegations against Meghan even though the staff were anonymous because Buckingham Palace commissioned an independent investigation. The findings were never published, yet you consider the allegations credible. So why are anonymous staff suddenly not credible when it comes to William?
We don't get the names of palace staff because they're employees bound by confidentiality. That's true whether the allegations concern Meghan or William.
Royal biographers such as Robert Lacey and Tom Quinn have interviewed palace sources over many years, and William's temper has been reported by multiple independent authors, not just one.
You also say William only loses his temper "at home." His household staff are still his employees. If they are carrying out their duties in his home, that is still their workplace. An employer shouting at staff at home is no less a workplace issue than if it happened in an office.
Ultimately, you can't argue that anonymous staff allegations are sufficient to believe Meghan bullied staff, while insisting anonymous staff accounts about William have no value at all. Either the same evidential standard applies to both, or it doesn't.