Hey, welcome to the real world:) This is your job now, so try not to take it too personally and don't forget to find a balance between work and life (yes they are different).
Jokes aside, I've been working with 2k - 5k line files in both python and JS for the last 10 years or so, in different code bases for various companies. That is, code I did not write but had to understand, extend and fix.
I've only worked with maybe just 2 super clean and well written codebases, for new prodcts/projects written by short-term contractors. The code was just beautiful and I learned a few things just by reading it. Both projects never saw a public release and the companies are long gone.
The projects with the superbad, just kill me now code, are moving along, slowly but steadily.
(also, FWIW, its Customers > Product > Code)