Photoshop 2020 (21.1.0, Mac version) has a weird bug in the "Liquify" filter. I have a layered image containing several image segments, some of which are partly off the canvas. When choosing the "liquify" filter and with "show Image" checked, multiple fragments of the background appear in segmented parts of the working Liquify window. Oddly, these fragments change depending on how "zoomed-in" I am.
In the attached graphic, the two sections of the bird seen at the bottom are not part of the image and are not present in the canvas I am working on — either as layers or as an added part of the background. There is nothing like them in any layer (beyond the part that occurs in the bird itself). They have been added to the canvas render in the Liquify window. The actual bottom edge of the real canvas occurs in this window at the dividing line between the top of these two fragments and the rest of the photo. Note the presence of two dark, blurred "legs" of the bird which I was adding to the water. Each of these legs is on its own layer. Both extend below the bottom edge of the canvas and into the right "ghost" image fragment (which should not be there).