Jagged edges when scaling down and rotating Smart Objects (with ALL interpolation modes)

When I scale down and rotate a Smart Object, I get subtle but significant aliasing. This does not occur when I do the same thing to a regular raster layer, nor does it seem to occur when only scaling or only rotating the Smart Object.

I created a gif comparing the results with a graphic that has been scaled down and rotated, one as a raster layer and the other was a Smart Object. 

Here, the raster layer produces the expected results (clean, slightly soft edges with little aliasing). But the Smart Object produces small but significant stair-stepping, even though it should, in theory, produce identical results. This problem occurs no matter what interpolation method I select in Preferences. These examples were both scaled down using Bicubic Smoother, which produces the least bad results. When using Bicubic, Bilinear, or Bicubic Sharper, the problem is worse.

The graphic being used is of a high resolution (6000x9330) and it is being scaled down by nearly 50%. This should be more than enough to produce smooth edges (and, in fact, it is—when scaled/rotated as a normal raster layer). Am I missing something?

System information:
2018 Retina MacBook Pro
Intel Iris graphics
MacOS Catalina 10.15
Photoshop CC 20.0.7 (though this affected at least two versions before it)