220GB vhdx file suddenly appeared in WDMyCLoudMirror

Windows 10.
I was checking various drives for large files to clear up space and found three vhdx files in this drive. Two, of about 70MB appeared at the same time 14th June. One of about 220GB - yes - 220GB - appeared 20th June. Photoshop Lightroom did have a couple of glitches where it stalled for a long time when I was moving a lot of files, but I don’t know whether this explains the vhdx. Would they have been put there temporarily whilst a large number of photos (40MB plus) were being moved? Or is this something else?