OK, I'm an IT veteran, electronics engineer at first, then integration, web development, now dept head. 35 years, but this is bizarre.
When I am on Spiceworks community, I occasionally see a horizontal black line scan up the page at about 3 cm/sec. Seems like a sync/scan issue, right?
When I first saw it I thought, "Oh oh. Is my monitor going?" Then I saw it on another monitor and thought, "GPU"?
Now I've realized it is staying inside the rendered browser frame and I've only see it on Spiceworks.
I'm using Chrome 104.0.5112.81. It moves with the browser to any one of the three monitors I have, and doesn't impact anything outside the window (e.g. doesn't scan all the way to the top of the monitor or over the browser tabs, address bar, or bookmarks).
I'm still observing but FWIW it seems to happen mostly right after I switch pages or otherwise abruptly change the image. I haven't seen it while I'm just stationary on a page reading posts.
Configuration is RTX 3080Ti with latest drivers, Dell U-series 1920x1200 monitors, confused user.