...whereas the rest of the spec omits "in the HTML namespace" when mentioning a specific HTML element, as per
https://html.spec.whatwg.org/#xml
Except where otherwise stated, all elements defined or mentioned in this specification are in the HTML namespace ("http://www.w3.org/1999/xhtml"), and all attributes defined or mentioned in this specification have no namespace.
What is the issue with the HTML Standard?
https://html.spec.whatwg.org/#has-an-element-in-list-item-scope says
(same for the next 3 definitions)
...whereas the rest of the spec omits "in the HTML namespace" when mentioning a specific HTML element, as per https://html.spec.whatwg.org/#xml