When I clicked this the title was asking how this was working. I think that's what this user was answering

Hi yes this is what I was asking. I don't know why the title has changed!

Moderators change titles when they break the site guidelines. The relevant guideline is "Please use the original title, unless it is misleading or linkbait; don't editorialize."

https://news.ycombinator.com/newsguidelines.html

The submitted title was "Wall-climber robot spraypaints big murals, any idea how its hardware works?", which is actually more baity than the original (wrong direction!). It's also the sort of thing that will strike HN readers as transparently promotional, prompting them to flag a submission.

Do you remember that titles on HN can change?