Having looked it up, the punch was thrown in 2013, after AMW said disparaging stuff about H behind H's back.
So, pre-Markle.
But (from the Guardian):
"Lownie’s biography, Entitled: The Rise and Fall of the House of York, also claims Andrew told his nephew that his marriage to Meghan Markle, now the Duchess of Sussex, would “not last more than a month”.
He allegedly “accused Meghan of being an opportunist and thought she was too old for Harry, adding that his nephew was making the biggest mistake ever,” and told his nephew he had gone “bonkers”, accusing him of not doing “any due diligence into her past” before they got engaged in 2017."
(I am putting off starting my tax return, before anyone asks if I haven't got anything better to do.)