I think this is from the Yoast SEO plugin, but not positive. It updated this morning, and I only noticed it today.
Every new post and draft (and if I update an already published post) has a custom field variable name “yst_is_cornerstone” showing with an empty value. It won’t delete. Deleting doesn’t do anything. Changing the value and name and hitting update results in it being re-added in addition to whatever I tried changing it to.
I’m worried it is some type of infection because the only Google result for “yst_is_cornerstone” brings up a sketchy page.
Anyone know what this is / how to remove it?