Google Soft 404 for a page titled What is a 404 Error?

In our marketing gloassary section - we have a page called What is a 404 error. For a number of years - this page has continued to show as a soft 404 in the search console pictured below.

Changing title, meta, content or anything on that page has not worked. The page returns a 200 OK when tested through the network tab on the devtools.

However, Google things this is a soft 404 error. No this content is not the same for multiple other URls, no this content is not a redirect or broken link of an old page and no this is unique content.

What gives ? Google !