Pretty sure that's just iOS behavior + app design. If notifications are off, apps will occasionally prompt again to make sure you didn't disable them by accident or miss something

No, the OS will not do that, nor is the developer able to trigger the system prompt again when they detect the user has notifications off. Only thing they can do is present their own prompt and link out to the Settings app for the app's settings. Can't even deep link to the app's notification settings.