A clarification on this paper:
It was published to Arxiv in 2019, but was not publicly announced because the event had been detected by military sensors and the researchers only had access to the data that was entered into the database they had been combing through. Confirming the margins of error on the original detection was complicated by the needed data being classified (presumably because the US DoD doesn't want the exact capabilities of its sattelites to be publicly known).
That situation was remedied on the 6th of this month, which is why it's just now hitting the news:
A small meteor that hit Earth in 2014 was from another star system, and may have left interstellar debris on the seafloor.
www.vice.com