The first to break this royal rule is what bride Meghan Markle did this time

After the guard wedding with Prince Harry, Meghan received “Military Palton” as a gift from the palace.

This special gift is usually given to the father of the bride, but because of the ongoing drama in Meghan's family, the decision is that gifts to the bride are given by the bride, breaking the royal tradition.

Also, her family name was not written on coat design, breaking another tradition. For example, Kate Middelton's family coat included the name Middelton.

A Military Palto or Coat of Arms was created for the Susex Duchess. The coat design, approved by Her Majesty Queen and General Thomas Woodcock”, is said to be announcing the Kesington Palace.