I personally am not protective about my code therefore it's o a public repo on GitHub, as requested for the entry, but there are a lot of people showing distrust in sharing their code. (can't really see why because it's not like someone would publish the code for the new GTA 6, but hey, it's their code and have the right to ask 😉)
My idea was that you don't have to add your source code to the store as a zip file in your itch game page, you can share the link to your repo or a public Google drive folder etc. when you submit your game for the jam. 🙂