The last 2 are what I'd expect from WDR. You can see the extra contrast and dynamic range. As you said maybe a slight issue with the plant next to the palm outside in the bottom one (looks a bit like an Acanthus - beware they spread like sh*t and are near impossible to kill, although I do have a way). Now compare that to the goat cam, specifically outside area where it's a lot more extreme:
I think I can see what's happening here now. The algorithm or camera metering, or both, are failing to deal with / meter the highlights properly. If it's the algorithm it's over blowing the lightening of the inside of the pen, causing the contrast to be lost, and it's applying the same setting globally to the whole picture rather than regions which is causing the already correctly lit outside area to go completely flat and lose all contrast. The level of lightening is also then causing the artefacts which give it the painted appearance.
You get a similar blown out effect without the artefacts (no HDR being applied) on an ordinary non WDR stills camera if the metering fails to deal with a window adequately. Point the camera outside and the room is too dark. Point the metering point inside, and the room is great but the outside becomes overexposed and a white out. The answer is, to meter a mid point so you get a compromise that lights both areas. More advanced SLRS can manage this better thanks to Matrix metering. The issue here though appears to be either the original camera isn't dealing with the original lighting dilemma in it's metering well, with the result that the WDR overblows the highlights beyond what is acceptable through applying a boost, or it's metering ok but the WDR algorithm is being globally applied to the picture and failing to take into account differing lighting regions. It could of course be a combo of both. Either way, I'd put it down to a firmware failing.