Other than announcement posts, I think HN members general post submissions whenever they come across them. Looking at the bug report, it was updated today, so it likely caught someone's eye.
A comment consisting of the single word "So?" is dismissive, particularly in a text-only environment devoid of tone of voice or body language. It doesn't convey any of the interest you've shown in your follow-up.
The title chosen by the OP is devoid of tone of voice or body language too. To me, the OPs phrasing seems borderline negative. Sounds like OP is either ridiculing the project for not fixing a bug for 10 years or perhaps OP thinks a bug fix is owed to them.
Yes, the submission title could arguably be better. Given the bug ticket title is "mixing ({...}) with VLA leads to massive breakage", there wasn't a lot to work with.
However, the title of the submission is beside the point. All of the things you're including now would have been great as part of your initial comment. None of that is conveyed in "So?".
A comment consisting of the single word "So?" is dismissive, particularly in a text-only environment devoid of tone of voice or body language. It doesn't convey any of the interest you've shown in your follow-up.