Learn how to insert a photo, picture or other image as a watermark in PowerPoint in this video from Microsoft. PowerPoint doesn't have a gallery of ready-made watermarks like Word has, but you can still manually put a text background in your slides to get that watermark effect. To indicate that your presentation is a draft copy, add the watermark text "Draft" to the background of your slides. Or add other text stamps, such as "Company Confidential" or your company name.

Learn more: https://support.microsoft.com/en-us/office/add-a-draft-watermark-to-the-background-of-slides-ea4cc5f5-ea5d-4213-9c7d-ed01a7952ed0