Having the same issue with VLC on Windows 11.
Preferences / Video / Output: changed from 'Automatic' to 'Direct X (Direct Draw) video output' - this partly resolved the snapshot issue. Snapshots now take, saving in the usual folder and are no longer green! But the snapshot tool is not working completely - it is missing the usual snapshot preview which would display then vanish in the top left corner of the screen.
I also have a linked issue with the 'Interactive zoom' (available under 'Effects and filters' / Video effects / 'Interactive zoom').
Before changing output to Direct X operating the Interactive zoom changed the whole picture to negative (bright white) colours. Now, with Direct X, the zoom just doesn't seem to load at all (picture remains the same, no zoom window overlay can be seen).
The issues seem to be linked, as both snapshot and zoom generate an overlay picture on top of the video image.
Any other suggestions from anyone?? VLC is an essential work tool for me, keen to get this resolved asap.
Update: messing with the settings, Open GL for Windows as the video output fixes snapshot such that the snapshot preview image has returned. Though it also seems a little unstable, as sometimes the preview is not working, and the cursor is disappearing when entering the area of video playback (re-appearing over menus etc). And the interactive zoom still doesn't work.