Received "Good" Condition Used 4K monitor from Amazon today. It's already glitching. What's the cause?

I won't waste too much time here typing up the story, I'll just let the video explain (I already typed up my case in the video description. But what is the cause of this? Is it a bad monitor, or a bad Displayport cable? I have very high doubts that my graphics card is to blame, as I've never had any problems with it.

That's the monitor it's the video control board. Return if you can.

It's very likely just broken, but it could be a bad displayport cable. Try another one if you have a spare.

So, an update. I've tried switching the displayport cable to a different port in my video card, and issue has not returned. Good thing I have three of them.