'grid-like' artifact

[Micusune]

I've encountered an issue while generating images with FLUX. The entire canvas of the image exhibits a visible 'grid-like' artifact, which looks like a subtle but consistent pattern of intersecting horizontal and vertical lines. This pattern becomes most noticeable in darker areas, such as shadows, fog, or smoke. On lower-resolution images (e.g., 1 MP), the artifact is less prominent, but when I upscale to 4 MP or use FLUX tools like Depth or Canny Control, the grid becomes very pronounced, even at 1000x1000 resolution. It resembles a fine mesh or screen overlaying the image. Is this a known issue, and how can it be resolved?

fluxtools-lora-depth-demo.json

[Lupin-IlI]

I get the exact same artifact when using flux checkpoints in forge. Same behavior too. It doesn't really show up until using hires fix and upscaling it, but I don't think it's related to upscaling... I can see the grid pattern in the early denoising steps.

I've tried using every upscaler, sampler, and scheduler. I've tried a range of sampling steps, denoising strengths during upscaling, a range of hires steps, and cfgs.

Once I see it, I can't unsee it, and it ruins every image.