Banding on reference Atomos Neon monitor, not on XDR monitor

I don't know if this is new, or if I've just never pushed some clips this far, but I'm seeing banding on some grades on my external reference monitor that is NOT showing up on the computer monitor.

Setup:
• Mac Pro, Apple Pro Display XDR
• macOS 12.6.1, Resolve 18.1.1, Desktop Video Setup v12.4.1
• DeckLink Mini Monitor 4K [PCIe card] — also tested with UltraStudio 4K Mini [Thunderbolt], same result
• ATOMOS NEON 24" Monitor, set to Rec709 (this is an SDR project)
• Source is Blackmagic RAW footage

Video Monitoring Settings are 4:4:4 12-bit, as follows:

Video Monitoring Settings

CleanShot 2022-11-28 at 13.13.04@2x.png (112.13 KiB) Viewed 100 times

If this were showing up on the XDR then I'd assume I'd just broken the file. But it looks fine on the XDR, while banding on the NEON.

So again, I don't know if I've just never noticed this and it's expected, or if something is wrong, and I'm wondering if anyone else has seen anything like this, especially if it's a new issue!

-Joseph