Currently it seems like if (for some reason) yt-dlp or whatever you're using the backend, fails to fetch the transcript of a youtube video. The error it shows the enduser is something about there not being a transcript available. Which isn't the case, there is. And when I let it try again, it succeeded.
So the error shown to the enduser should have been "Transcript can't be retrieved, try again in a minute" or somehting.
