Language learners: what mistake survives every correction?

I'll go first. I'm learning German, and I said "ein App" instead of "eine App" twelve times in three days. ChatGPT corrected me every single time. Every new session, it forgot we'd already been through this.

I think everyone learning a language has one of these. A mistake that survives every correction, every app, every teacher. Spanish learners mix up ser and estar for years. French learners guess genders forever. In English it's prepositions ("depends of", anyone?).

That's the itch behind mitDeutsch, launching here July 26. Any AI chat explains grammar brilliantly, but none of them remember YOU.

So I built a system around the chat: it keeps a profile of your recurring mistakes, groups them by root cause, and generates your daily lessons from them until they stop showing up. German only for now, other languages depending on how this goes.

So, whatever language you're learning: what's the mistake that just won't die? And if you've tried learning a language with ChatGPT, where did it stop working for you?

(If you're curious what the fix looks like, there's a trial lesson on mitdeutsch.com, no account needed.)