With the item's name colored, shulker box don't show the item's color correctly

This report is quite difficult to understand as little information has been provided regarding the problem. With that being, would MC-129565 happen to describe your issue?

Yes, it's duplicated.

First, my thought was that the style of item name must same in shulker box's description because the item inside have seemly same style of item name. But in fect, same color like diamond helmet and the paper I named by command looks different in shulker box, like diamond helmet is white, but renamed item is in aqua, also the style of the number behind.

Second, why both of the commad-renamed item seems different in description of shulker box, like why the number behind the blue italiced named diamond sword and aqua named paper looks different?

Finally, as you said, my report is not fully described the issue I encountered, and I forgot this issue for a long time, so thanks for reply and I'm really sorry about no replying for a long time, and also it was been reported earlier by others.

No worries! However, thank you for confirming that MC-129565 describes your issue. 🙂