Quicktime player video record and codec

When I do yideo recordings with latest Quicktime player (10.4 using High Sierra) with qualtity set to max, the video quality is looking very good while recording. But when watching the recorded video it looks much worse, and thin lines are not good looking, as they appear with stepped lines. (don´t know the english word for this effect - happens also if you enlarge a digital photo more than 100%)

I am wondering what is here going wrong. When I check information for such recorded video, it tells me apple prores 422. But I thought that prores 4444 is the right codec for max quality recording?

I been searching now for hours about that, but did not find any solution or idea, I don´t know if that is a codec problem, or normal. If I do same recording using Quicktime Pro, with quality set to native, I am getting best results, and no stepped lines.

Anyone an idea about that? Thanks!