Since updating Photoshop and Lightroom, I've noticed that the aux:lens metadata field is being deleted from my images on import, such that there is no lens listed after import. I've determined that it's Camera Raw 9.5 that seems to be the culprit, as lens metadata is retained if I use an older version of the DNG Converter v8.8 to import the same images.
For example, I had an image shot on a Sony RX100 III at 8.8mm. If I import this image with the old version of DNG Converter, and then open the converted DNG in Photoshop, the lens is reported with the full-frame equivalent focal lengths, i.e., 24-70mm F1.8-2.8, and the raw metadata has the correct aux:Lens field (24-70mm F1.8-2.8).
Conversely, if I import the same image directly into Photoshop or Lightroom, the metadata will display the correct focal length, but will not display the lens information; Lightroom reports this only as "unknown lens," and in Photoshop the aux:Lens field is missing completely.
For now, I will use the old version of DNG Converter as a workaround, but this is inconvenient, and really should be fixed.