34GK950F brightness dimming during use?

I recently picked up the 34GK950F, and one reason I wanted to go with this model is the extra color gamut for hobby photo / development work with a MacBook Pro (HDMI 2.0 for 60Hz @ 3440x1440) hooked up along with my Gaming PC (DisplayPort @ 144Hz).

I've been noticing these sort of "dimming" steps happening when I change the content of what's on the screen. Opening [this article](https://www.144hzmonitors.com/monitors/aoc-ag273ug-aoc-ag353ucg/) in a browser taking up the right half of the screen, and then scrolling from top to bottom and back a few times seems to consistently trigger it. The screen dims noticeably, more the longer I scroll. Then, if I let it sit for 5-10 seconds, the brightness comes back up. It's very weird, and makes it difficult to trust any calibration. It happens in macOS and Win 10, it happens on HDMI or DisplayPort, it happens no matter what refresh rate setting or frequency I use. Firmware has been updated to the latest, just in case. And it's noticeable even when the display is calibrated down to \~120 nits. DFC is off, the 1mS anti-blur feature is off, but there definitely seems to be something in the display mucking with how much light gets emitted.

Has anyone else seen this behavior? Is there some setting I've missed?

If this is something inherent to this display, is there another WQHD display out there I should be looking at instead? Ideally at least 100Hz native and greater than sRGB gamut.