This is a critical detail. GPT-4 is much better than 3.5 for programming, in my experience.
Yeah I really don't understand why research is still being published that uses GPT3.5 rather than GPT4 or both models. ~500 programming questions is maybe a few bucks on the API?
Because 99% of users and probably 95% of programmers are using the free version while almost no one is using the paid version.