Rank Math has recently started a weird behavior for posts and pages where a Featured Image / OpenGraph Thumbnail is not defined. Instead of falling back to the default OpenGraph Thumbnail set in the plugin settings, Rank Math instead grabs a random image tag from the page!
This creates a weird issue where posts and pages shared on Facebook or Twitter now have odd icons or decorative images appearing as their featured image!
The only solution is to manually go in and define a specific Featured Image or OpenGraph Thumbnail for every single post and page on a website. This bug has rendered Rank Math’s default OpenGraph Thumbnail setting entirely useless.
Rank Math is the only SEO plugin I know of that has started this unexpected and unhelpful behavior. If a page or post on a site does not have a specific Featured Image or OpenGraph Thumbnail defined, it should fall back to the default OpenGraph Thumbnail specified in the Rank Math settings, not choose some random image from the page.