Google removed outdated structured data documentation, but instead of returning a 404 response, they have chosen to redirect the old URLs to a changelog that links to the old URL, thereby causing an infinite loop between the two pages. Although that is technically not a soft 404, it is an interesting use of a 301 redirect for a missing web page and not how SEOs typically handle missing web pages and 404 server responses. Did Google make a mistake?
If you’re looking at it just from the Changelog, then it does look like a mistake. There’s another…
