Hello,
I suggest checking if this issue started after a Windows update or system change. Make sure your save location has permission and enough space and try saving to a local folder like Pictures instead of a cloud folder. Ensure Snipping Tool is updated via the Microsoft Store and restart your PC.
If it still doesn’t work, reset the app by going to Settings > Apps > Apps & Features > Snipping Tool > Advanced Options > Reset. This should restore normal saving without affecting other files.