Below is Luffy's pirate flag.

I wonder if the one in the middle is Cardo's.

At the bottom is the pirate flag with white beard.

Because of Ace, Luffy was friendly with White Beard in wartime. Later, Luffy was released, and his domineering attitude blocked the sailors' execution of Ace. White Beard knew Luffy was unusual, so Roger the One Piece gave his hat to Jencks the Red Head. Why is this hat with special significance given to Luffy, but I am betting on a new era? It can be seen that Red Head recognized Luffy, and White Beard began to understand that Red Head had expectations for Luffy. But the boy with white beard was still too weak to see the straw hat. When Luffy used his hegemony, White Beard knew that Luffy was also the chosen king, and not everyone could have hegemony. So White Beard planned to put the hope of saving Ace on Luffy, and gave instructions to the captains of each team of White Beard Pirates to protect Luffy.