Hacker News Reader

Same here, on a Dell P2421DC (2560 x 1440 @60 Hz). It is especially noticeable on darker colors (grey or black backgrounds).

Same on my Dell. What seems to stop it is turning off HDR and back on again (using the monitor's OSD menu)

found that something like this fixes it https://youtu.be/t6jlhqNxRYk?feature=shared&t=8468 play it in full screen for a few seconds

Same with Dell P3223QE.

yeah that happened here too. Was it an LG?

Yes! It's an LG Ultra HD running at 2560x1440 @ 60Hz

Same with an LG running at 2560x1080

Now what is causing it?

Same monitor here. Damn strange. I'd experiment more if I didn't need to work with it. Keeping the monitor off for awhile seemed to help , but a quick off/on didn't.

Yup, I turned it off, disconnected it from my Mac and left it for a minute, then rebooted. All seems fine now.

Capacitors needed to relax...