> HN commenters have a far greater history of that.

It may very well be true, it is also true that HN commenters can be quite good at spotting math errors. The broader point being that people make mistakes sometimes or even that people sometimes don't have the same knowledge and information as others.

> researchers trained for years and invested a long time on this work; the HN commenter probably invested a minuted or two

Or it can also be postulated that the researchers were highly focused on the aspect of the work they were trained and interested in and may have lacked focus on the auxiliary fields. And that the HN commenter, while only spending a few minutes on this, was knowledgeable about the auxiliary field and immediately spotted a potential issue.

This is actually great and why its good to get papers published and read by a wide audience, because nobody can be good at everything.