Are you using the Adobe Media Encoder and the YouTube Presets? Do you realize that YouTube will re-compress your footage and deliver it at what they feel is an optimal frame rate and frame size based on the connection speed? Almost all streaming services will re-compress your footage and the quality will suffer greatly if you do not follow their guidelines. Without complete workflow details and project specifications it's not very easy to say what is going on but I suspect that something in your render does not match the YouTube specs so they are re-compressing it and adding artifacts.
4K is generally not accessible to most of the public because of their connection speed. 60p is also generally not a good idea.
I did use the presets prior to trying my own settings and the result was the same. I was then advised to try render at 4K and it produced the same results.
I think YouTube is just re-compressing your footage. Try putting it up on Vimeo. The color levels look awfully hot to me and that could be causing edge artifacts. I'm also wondering if you have pushed into (scales) the original footage because this shot has no edge artifacts:
and this on does. It looks like scaling + compression artifacts to me:
Did Rick's advice help you get better looking footage on YouTube or Vimeo? Please let us know or if you need additional assistance.