Has anyone here experienced a sudden "quality" improvement in their foreign language skills?

I know this is kind of a strange topic so i'll try to explain it:<br><br>I've been learning German solely through Duolingo for the past 2 years and a half. (3 years, if i include the last 3 months when i decided to get serious about it)<br><br>So i've been consistently using the app everyday to the point where i've gotten to a 771 day streak.<br><br>Things were going great, as i got to C2 level in December 2023. Around that time, i was able to fully understand chapter 1 of Faust (in german ofc) while being able to pronounce the words perfectly in my head.<br><br>After that, i decided to grind more, develop a more consistent pronunciation and be more confident while speaking. I can now comfortably speak german with my girlfriend, who is german, although she has to speak slowly for me to fully understand what she says.<br><br>Long story short, i went from B1 to C2 in 3 months. 90 days.<br><br>I know it sounds crazy to go from B1 to C2 in 90 days in Duolingo, but that's the fact.<br>Now i can confidently say that i'm able to understand most of what Germans say, except from some complicated words, or very technical german words. I can fully understand every german word if i get to see it written down or inside a sentence. The only weird thing is that i have never studied any technical words, only random vocabulary that Duolingo threw at me, and i've only been reading Faust (which should have technical words for sure).<br><br>I went from being able to understand Faust and other random written things, to having a hard time understanding spoken german. This is true, because when i first started to learn german, i could understand spoken german pretty well. And then it got harder and harder. How does that make sense?<br><br>So now, i'm able to understand most of what Germans say, even if they speak pretty fast, and the only thing that i struggle with is the spoken german of elderly people. For some reason, their pronunciation is always so bad that i end up struggling to understand what they say.<br><br>I'm not trying to brag about being able to understand german better than before, but this is a weird phenomenon that i've never experienced before in my life. Am i going crazy?