For me, both Ctrl+Enter and Shift+Enter do the same thing as just pressing Enter. All three just close the textbox without saving changes.

Even if this is the default by design, I would argue that it is counterintuitive and provides a poor user experience. Typically pressing “Enter” should do things like “Accept” and not “Cancel.” Further, even if it does cancel, it should only cancel the link insertion. Instead, pressing enter while inserting the link actually cancels all changes made to the textbox.

I have had multiple situations where I have written paragraphs into a textbox, and then added a link, pressed Enter after typing the URL, and then everything is cancelled and I lost all of the paragraphs that I had written.

I would argue that, for the benefit of a more intuitive and user-friendly user experience, the default behavior should be modified so that pressing Enter simply accepts the link insertion.