There is also a (related, I assume) PR to remove the search syntax page from being published entirely[1]. It's dated December, so it may be fair to assume this has all just been documentation-publishing that hasn't been done yet, as others have posited. That says nothing of the rationale/efficacy of such filtering/syntaxing, though.

[1] https://github.com/duckduckgo/duckduckgo-help-pages/pull/152