I pushed build 4.1.14 to App Store Connect, and it got approved. It's in the Ready for Sale state. I realized there's a major problem with it, and don't want people to download it. Is there a way to un-publish it? To go back to the previous version (4.1.13) that I had before? Or to submit a patch or something that I don't have to wait a day to have approved?
No, the best choice you have is to submit an urgent fix build for expedited review.
Expedited reviews You can request the review of your app to be expedited if you face extenuating circumstances, such as fixing a critical bug in your app or releasing your app to coincide with an event you’re directly associated with. Expedited reviews are granted on a limited basis and we cannot guarantee that every request will be expedited.
Critical bug fix. When submitting an expedited review to fix a critical bug, include the steps to reproduce the bug on the current version of your app on the App Store.
Next time, you can try the Phase Release in App Store. This type of release can be canceled.
BTW, the expedited review is a limited request. Don't abuse it.