I think you are looking for :h :diffoff which removes diff options of the two buffers of a two-way diff.
This is mapped to dq in Fugitive.
You can go back to diff mode with Fugitive's Gdiffsplit.
Besides, the default for Enter and o in Fugitive's status window is to open the current version of the file, while dd is supposed to show the two-way diff.
I think ...