There are two papers linked at the bottom of the not-so-fine article, both leading to "green lock" unpaywall https://research.lib.buffalo.edu/articleaccess/unpaywall https://unpwaywall.org/ destinations.

The articles correspond to the following arxiv preprints:

https://arxiv.org/abs/2112.05171v2 [Quantum Hair and Black Hole Information]

which is an overview work published in Elsevier's Phys.Lett.B on an open access basis; and

https://arxiv.org/abs/2110.09386 [Quantum Hair from Gravity]

which is the main work (published to APS's Phys.Rev.Lett) that the not-so-fine article attempts to summarize.

Links to papers are at the end of the article