Just to be clear, I wouldn't remove the label on mobile entirely but just not make it fixed. In the sense of putting it inside the scroll container.

I only had time before to test it on mobile on my commute. Having seen the desktop version now I understand your concern. Maybe there is a way to just reduce the size of the information a bit but still keeping it structurally as is? I also think that most people can identify the source of the information just based on how it is structured (longer texts for wikipedia, youtube/twitter/reddit with its own branding, etc.) but we would need more opinions on that.