While shift-dragging objects green plus appears and picture clipping file is created.
This issue is intermittent, but when shift-dragging an object in order to maintain vertical or horizontal position during movement, a green plus will appear next to the cursor and upon release, the object will snap back to its original position and refuse to be moved until you use the Cmd+Shft+B shortcut, which seems to clear it temporarily. However, if after that green plus appears you drag your cursor off-window to the desktop, a macOS picture clipping file is created. I have been unable to locate any settings for adjusting the behavior of mac's legacy clipping feature, so I'm hoping this can be solved on the Adobe side because it is infuriating.
Chris Wakeling commented
I have a created a screen recording of the green plus sign behaviour. For me the green plus icon appears when shift dragging objects as mentioned but disappears when releasing the mouse/shift buttons. I'm not experiencing the picture clipping files.
Here is the screen recording on Illustrator 26.4.1 on MacOS Monterey 12.5.
Bug appears at 0:31 and 0:55. Although there is no sound in the video you also hear a "boop" sound when the green plus sign appears indicating that something is wrong.
Hope this helps Adobe fix the issue.