A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
Here is the MS propaganda for the feature
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It says
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The first time you try out PowerPoint Designer, it may ask your permission to get design ideas for you. If you want to use Designer, select Turn on.
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So look on the ribbon for an option to turn it off
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This page https://presentationgeeks.com/blog/powerpoint-designs/ Shows hot to turn the feature off
<snip>
If you can’t find or select the PowerPoint designer, you will need to turn the “design ideas button” on. To do this you will need to select File > Options, and in General, select Automatically show me design ideas in the PowerPoint designer section and check the box. You will notice there are two checkboxes in this section. 
The first checkbox is “Automatically show me design ideas”. Where you can ask for design suggestions at any time, select “design ideas” in the Design tab” and the second checkbox is ” Automatically show me design suggestions when I create a new presentation”.
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