Submissions related to HN's policy / editing of titles come up very frequently. It is explained on the Guidelines [1] page.

[1]: https://news.ycombinator.com/newsguidelines.html

And... yes. Obviously I submitted "How HN Changes Submitted Titles"

Is there an explanation?

I just submitted a Show HN post and noticed the system change "JS" to "JavaScript". I've never noticed these changes before; still I found the UX pleasurable - it told me that the change had pushed my title count over the 80chars limit and invited me to edit it.

For what it's worth, I'm all in favour of an autocorrect that attempts to cut down on click-baity copy in links. I still get caught by them on other sites.

There are a few anti-clickbait title filters. Questions posed in the title are changed to statements. Either it is or it isn't.

In this case, "HN Changes Submitted Titles" is more informative and concise. Your post doesn't answer "How", it merely states that changes occur.