Public decks on Slides can be copied into your own account and used a style guide for a new presentation. The copied deck visibly references the original deck and promotes its author. The intended use for this feature is templating, every deck on Slides with copying enabled is available to you as a style guide to author your own content on top of.
Making a copy
The button for copying a deck is available on both the deck and profile pages.
Toggle Copying On/Off
Copying is an optional feature. If you would like to toggle it on or off your deck, you can do so in the deck settings panel as shown below: