An hyperlink put in a TextFlow is managed like one rectangle (cf. TextFlow "Any other Node, rather than Text, will be treated as embedded object in the text layout. It will be inserted in the content using its preferred width, height, and baseline offset.").

This is not natural, relatively to web. I would appreciate if text of an Hyperlink is flowed like a Text node because text before an hyperlink can be highly spread on its line when the hyperlink goes globally to next line.