Our current version of comments has a nifty feature that allows you to use simple keystrokes to do things like skip to the next unread comment (j), reply (r), recommend, etc.
However, some people rightly noted that having “f” as the keystroke to recommend a comment could have the effect of accidentally recommending a comment when you were using the browser’s keystroke command to find text on the page (ctrl-f or command-f). So we’ve changed it, so that recommending a comment now uses “shift-L.” Happy commenting!