Magazine style ads are text ads that we convert and render as "display-like" ads. When a text ad wins an auction for an image-only ad unit, we render the ad in the magazine style format. If you’re a publisher who prefers to serve "display ads only", then you’ll benefit from magazine style ads as they open up additional demand for your ad inventory while also delivering the aesthetics quality of display ad creatives.
Magazine style ads are only applied to ad slots that are opted in to "display ads only", and not to ad slots opted in to "text and display ads". Be aware that in display-only ad slots on your site, text ads may have been rendered as magazine style ads.