Changed Keyboard Shortcuts and Gestures in Photos 5.0 on Catalina

See the full list: Keyboard shortcuts and gestures in Photos on Mac - Apple Support

There are new gestures to move quickly between the Days, Months, Years and All Photos.

You may notice, that the keyboard shortcuts to delete a photo have changed. "Delete Photo" has vanished from the contextual menu, when viewing an album, see: How to delete photos while viewing an Album in Photos 5.0 on Catalina - Apple Community