2.92 version. New file. Object in viewport.
Material Properties!Surface!Roughness = 0
Material Properties!Surface!Transmission = 1
Material Properties!Settings!Screen Space Refraction: ticked
Render Properties!Screen Space Reflections: ticked
Render Properties!Screen Space Reflections!Refraction: ticked
Object appears in Eevee Material Preview with viewport's dark void background with a Blender-default garden picture file that fills the object, and in 6 DOF the garden imagery fills all of it.
Now I drop a sky dome over it, and then orbit:
Where the sky dome appears behind the refracting object, the Blender-default garden file imagery disappears,...but then reappears, resolving into some kind of cube of its own in the refraction. (The coral colored box is a separate entity.)
The garden file imagery is here, in a shader/texture provided as a default by Blender:
How can that garden image be turned off inside the refracting object (at the very least when the sky dome appears in the background behind the refracting object)?