Area surrounding work area a jumbled mess in RGB

Hi all,

What I've always thought of as the "artboard," the area surrounding the actual work area (but apparently "artboard" is now some sort of new feature?), has become a nightmare when in RGB mode. As I zoom in or out, or scroll, that area—previously dark gray—picks up the colors of my image, and fills it, constantly changing, in a jumbled mess of 8-bit blocks and lines. This does not happen in a Grayscale or CMYK document.

I've updated Photoshop once since it started, but nothing changed. Wildy frustrating. Anyone know what's going on?

Screenshot attached.

Thanks much,

Chad

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PS v22.5.0

iMac (Retina K, 27-inch, 2020)

OS: Catalina 10.15.7