Users don't seem to love the new Google Photos editing UI that has just started rolling out, complaining of missing features and too much change.

On the Backup page, scroll down and select "Back Up Device Folders." On the Device Folders page, you’ll see a list of folders containing images on your phone. To prevent a folder’s images from being uploaded to Google Photos, turn off the toggle next to that folder.

The perspective correction tool in Google Photos was used for straightening out flat, square objects in photos; think a document on a table or a painting hanging on a wall. You could manually define the four corners of whichever object in the original image, then Photos would distort the entire photo to square up the area you defined.