Followup: The final note from @sriram gives me a further hypothesis on how I might have spiraled into the situation. When I updated the Brave configuration, it appears I needed to reset “all scripts allowed” on all my trusted sites as I visited them. That would have included, of course, DDG. On the first search from the context menu using DDG as the default, Brave would have given me the message that javascript was disallowed. I then would have reset to “all scripts allowed”, but, because I was already redirected to the “…/html” site for that first search, it wouldn’t have returned the page content that I was missing. After that, the “…/html” site was captured in the history and any diagnostics that I did by typing “DuckDuckGo.com” in the search/location bar would have been affected and autocompleted as “DuckDuckGo.com/html”, given my usual habits of hitting return quickly. Hence, what appeared to me to be a permanent problem. Thanks again for your help.