usability: Should a "Close" button in a modal dialogue message always be in the same position and style?

In general, we place the separation / distance between two buttons (in the example on the right) when one of the buttons does something destructive (such as deletion) and we do not want the user to touch it accidentally when trying to perform a non-destructive action. . In this case, it is probably okay to move the "Close" button next to the "View order history" button.

If your customers choose "Close" much more than "View order history" (which you can track through analysis), it would be better if "Close" is the main button; Consider deleting "View order history", since there is already a link in the text of the dialog.