In the past, when you made edits to a photo and saved it a new photo would appear which would be the edited photo. In the Gallery you would see the original and the edited photo.
Now, when you make edits and click save it hides the original and only the edited version shows up in the Gallery. To return to the original, edit the changed photo and click Revert near the top left of the screen. This shows the original unedited photo. Then you can click Save and have the original showing in the Gallery.
To go back to the original experience, when you are done editing, click the 3 dot menu and select "Save copy". Now in your Gallery you will see both the original and the edited photo... just like the old days.