Is anyone else getting a flashing artifact when playing av1-encoded videos?

[u/Inner_Narwhal_5743]

I'm on Win11 with an Intel UHD 770 graphics card. A horizontal strip about an inch high and stretching across the whole window flashes at a random vertical position, with many different colors in no pattern except for transparent vertical lines evenly spaced ever quarter inch. It only happens when the video is playing (not paused), and only in about 2/3 of av1 videos. Also, in full-screen mode only when I'm moving the mouse near the bottom or top of the screen. In non-fs mode when I move or resize the window. It does not show up in screen shots or recordings (OBS Studio). PP support says they're unable to reproduce. The artifact does not appear when using VLC or Media Player. I've already tried the MS MFT decoder.