Hi Bob,
While this does look a bit like Earthshine, it has a very different cause. It's the thermal signature of Venus' surface glowing in the near infrared, which can then be picked up by cameras with appropriate filtering as Venus' cloud deck is relatively transparent around some wavelengths, incl 1,010nm. The technique has been practiced by amateurs since the early naughts. For a good example of what's possible
check out the work of Australians Anthony Wesley and Phil Miles, who have been very successful with this kind of imaging. We've been using other equipment as well incl significantly larger optics, but that data is still being worked on. This rig was set up alongside specifically to see what's possible with basic gear.
On the subject of light being refrected off the night-side of Venus, there have been occasional reports of
'ashen light', which may indeed be caused by Earth (though other theories exist). I've yet to observe it (visually or otherwise), but I agree with you it may actually be a thing. We know Venus can cast shadows on the night side of Earth, i.e. visibly illuminate the ground, so I don't see why a brilliant gibbous Earth seen from Venus (-6th mag or thereabouts??) couldn't do the same thing on its cloud deck, especially on such a high-albedo canvas.
Fun stuff