Where did Windows 10 save clipped images using Windows Key + Shift + S?
The new Snip & Sketch tool copies to the clipboard but will also save the image in a temp file. The temp file of the image is stored in AppData\Local.
C:\Users\%USERNAME%\AppData\Local\Packages\Microsoft.Windows.ShellExperienceHost_(a string of numbers and letters)\TempState\ScreenClip
Source: https://www.reddit.com/r/Windows10/comments/aia21t/snip_sketch/elt5ajt/