I'm on MacBook Pro 2017 15in running Public Beta 1. When playing video in safari in windowed mode, small graphical glitches start to appear soon. I took a picture of them. They look like small colorful squares that flicker slightly. When I move the window or move the mouse over them, they disappear, but reappear later. Any idea what it is? I hope it's not GPU problems, but just the buggy OS.
Here's the picture:
Here's the picture: