The formal signature stands for “His/Her Highness” and is designated for active royals. According to royal expert Stéphane Bern, Meghan’s decision to use HRH despite Buckingham Palace stripping it from her and Harry when they left the U.K. as a family unit, made William even more vengeful toward his brother and sister-in-law.
“These three letters have reignited tensions at the very heart of the monarchy,” Bern told a news outlet.
A second source claimed William was “deeply frustrated” over the formal use, especially for commercial gain, as it is highly against royal practice to use their titles to make money.