If I turn down the settings they do go away. I have everything cranked to the max! I have done a little vid as well and added it to the bottom of that post. On mine they are there until you move then they go. Have a look at the video and you will see. In my eyes they look like they should be there or are some graphics setting. I might stick vega back in and see!
The other thing I question... after that room they go! I dunno man, im going to stick a vega in and have a look. My bet is that they are meant to be there or are a setting of some description. I could well be wrong.
Because you are saying they go away if you turn down the settings; Have you tried to bump up the voltage while you saw those things ?
I saw some weird artifacts with lights and sparkles in heaven benchmark while tuning the card. Those where first signs of instability. After slightly more core or reducing the clocks a bit down they disappeared.