Yoast Robots Meta
Because of French copyright law, every page using Yoast SEO plugin will have the following robots meta bit added to its robots meta string — unless a page is to noindex or nosnippet:
max-snippet:-1, max-image-preview:large, max-video-preview:-1
If you are really keen to change the robots meta value, you can do it in a filter called wpseo_robots.