I have been using the add-on for a long time and found it to be very useful. There is, however, at least one issue with the new version (2.0.0). The link icon that pops up doesn't vanish any more when the page is printed (using a "print" link in the webpage itself), but remains visible on the printed page.
I think there was an option to turn off the printing of the icon in the old version of LinkAlert, but I cannot find it in the option menu of version 2.0.0 any more.
(Windows 7 Ultimate 64-bit, Firefox 57.0.2 64-bit, German language settings)