Generally, this happens when you have entered the [unsubscribe] replacement tag in the "URL" (for setting up a hyperlink) and in the "Display text" for this hyperlink as well, in an Email editor. Due to this the complete hyperlink text is displayed instead of display text.
Please refer to the image below. Here the [unsubscribe] tag is entered in the display text:
Please be advised, the [unsubscribe] tag only be used in the URL section.