Quoting the upstream source:
https://www.websiteplanet.com/news/cigna-breach-report/
Cigna Security’s response: “Thank You for your email to our responsible disclosure site. In review of the issue, the data is intended to be public as part of our Transparency in Coverage program and as per Federal regulations which began in 2022”.
[end quote]
Though I can't imagine it was left exposed this way on purpose.