God, even before the AI bullshit and CEO defending it, why did people use Duolingo. You're not learning a language, you're learning how to play a game that is coincidentally about languages. The only good thing Duolingo does is getting you motivated to learn, and teaching basic vocab. That's literally it. The best advice I got on that platform when I used it as a kid was how it was incorrect, and where I should go to learn from better sources, which is probably why they got rid of forums and comments.
Edit: Forgot to mention the awful and scummy monetization of making people wait to do lessons because of the heart system, while giving paid users unlimited lives. I've literally seen a comment on Lemmy where a user said they used a cracked version of Duolingo to get unlimited lives for lessons. Why should you have to crack your language learning app to make it bearable?
YouTube is free, and almost guaranteed to be better. Mango languages is free for students and library card holders apparently, haven't used it, but others seem to like it. Get yourself some books to read, a textbook/grammar book to practice shit, and watch content online for listening. Use exchange apps for speaking. Use multiple resources, one resource that claims to teach it all is probably lying and can only do so much.
Edit: Not hating on the meme btw, just ranting
Surprised that worked for you, but congrats. Did you only use Duo, or did you use multiple materials along with Duo?
I just am curious, since I and many others who criticize Duo seem to see it as a tool that should only be used for beginner knowledge and introduction to a language. Duo also don't do as many listening examples compared to other apps right? You must be skilled at listening input.
Edit: Here's another example of a person (skip to 7:20) who did mostly just Duolingo for 2 years and struggled on the JLPT N5 (lowest level)