Images uploaded here have a different WB.

I usually export from RT using RTV4_Large. Gthumb, displays the image just like RT does. Uploaded to Facebook, images look just like they do in RT.

When I upload here, my images look different, leaning considerably towards blueish, colder tones.

I think here you’re getting sRGB.

I don’t know, but for instance, the preview window shows the correct color, while the post itself does not.

See here, check the sunflower petals.

At one point, the forum started keeping the colour profile. Maybe resized images don’t retain it, or the act of resizing changes the colour of the image. The latter will definitely happen; not sure about the former.