[estaseuropano]

Can only agree. Duolingo gives some basic vocabulary but after that basically is useless, especially as the way it teaches grammar forms (and on the mobile app barely any explicit rules) is 100% useless. Native speakers looking at example sentences in the target language are often shocked at the nonsense that is provided.

But worst for me is that it wastes time. The unnecessarily ineffective repetitions, all the features and ads intended to upsell 'Pro', etc. There are dozens of other apps that do it better for free (e.g. good old Anki, or newcomers like Clozemaster) and when on a desktop a whole wealth of professional learning resources are available, both old ones that are now public domain, the world of wikis and collaborative learning and flashcards, and no-profit materials. For instance lots of organizations fund free courses, e.g. the EU funded a bunch of sites for learning languages, like https://deutsch.info, and national broadcasters like RF1 (French), DW (German) provide great professional and current materials. Podcasts and youtubers teach any language imaginable, etc.

Try Duolingo to get a taste, but after a few lessons look for your language online and you'll find much better stuff.