The machine generated content was already bad. I don't know if this AI transition will make it better or worse but I swear Duolingo was among the worst of apps I tried. People say it's ok to use supplementary when you have a 10 or 15 minute break but I think sentence mining or watching YouTube videos with subtitles is a better use of those minutes. I avoid telling giving this advice to people in real life because it seems dismissive of the time they are spending.