Opening up a view file, and first thing I see is a function accepting 13 parameters.

I don't know where to start, so much wrong..

Kill me.

@Kashmir I don't quite know what the function does, but it's called filterList(); and spans ~300 lines.of if's and loops.

The system is a customer system that keeps tracks of customers and orders and data about customers.
Made in a hella old version of codeigniter

(It's a client system, not our own, and one we inherited from a previous dev)

I once write a function with 19 parameters. Can do it better using structs but currently doesn't have time to refactor it.
Anyway, my work is scientific computing so maybe I still can get away with it. But I agree with you, in real-world programming, I would frown upon it.

A code smell so bad I’d rather be locked in a bathroom with real bad smells

I eventually spend some time looking at it, and it looks like something that is relatively easy could be replaced by a SQL query.

But that function is so engrained in the system that my fear of doing so is overwhelming,. due to the number os possible bugs i'd introduce

Meanwhile the method to generate an explosion in the Rimworld Modding API accepts 28 parameters