Hi! I've been doing Duolingo for a few months now but I had to stop for a while because of school, so I don't go on as much. But when I do I realize that on the bottom it says "Improve Weak Skills", dueling was my favorite part of the app and a perfect way to put my skills to the test and now it's gone!! Is it because I haven't been on in a while or an update or what? Thank you for your time.
It has been gone for months now. It was removed without an explanation.
Like Lenkvist said, it was removed without warning or explanation. However, Duo dev tylrmurphy later mentioned (well after the fact) that duels was removed because it was having a negative effect on learning according to their metrics, and that it was taking up screen space they'd rather use for something else.