OK I've looked in the logs and here's what happened.

The originally submitted title was: The workers behind Meta’s smart glasses can see everything.

That title was created by the submitter; it's not the original title and it's not a verbatim line of text from anywhere in the article.

It's also, arguably, clickbait, which I gather is why another moderator changed it to: A hidden workforce behind Meta’s new smart glasses.

Their intention was to make the title less baity and be closer to a verbatim line from the article (a line in the subheading is "Behind Meta’s new smart glasses lies a hidden workforce").

That's what triggered all the complaints.

I then changed it to a title that is a verbatim string from the HTML title, with the baity part at the end removed. That is bog standard title editing of the kind I've done every day for the several years I've been doing this job.

> First-ever in-utero stem cell therapy for fetal spina bifida repair is safe, study finds

"Is safe" is not an absolutist claim, but even since your comment was submitted, another moderator has – correctly – changed "first-ever" to "first", because "first-ever" is absolutist and baity.

> The large number of replies this renaming got in a short timeframe is because it's not in line with what we're used to when it comes to title changes on HN.

What I've described above is what HN moderators do several times each day. I think the reaction to this one is because it's a topic that inherently gets people riled up (understandably), and people's riled-up-ness will spill over to any perception that we're "suppressing" the story. But we're not suppressing the story; it is still at top spot, and it will stay on the front page for several hours and everyone will have every chance to read it and discuss it.

The title we've arrived at now is the one that's most consistent with the guidelines.