Personal identifying information for 1.5 billion users was stolen in 2021, but from where?

Threat intelligence company Black Kite found that the majority of attacks were against healthcare providers, involved ransomware and succeeded thanks to software vulnerabilities.

source https://www.techrepublic.com/article/personal-identifying-information-for-1-5-billion-users-was-stolen-in-2021-but-from-where/#ftag=RSS56d97e7