Researcher: Apple
Link: https://www.wired.co.uk/article/iphone-jailbreak-ios-12-4-update
Helping out the security research community or general incompetence? A popular SockPuppet vulnerability found by Ned Williamson, a Google security researcher, was fixed in iOS 12.3 but was such a fun bug it was reintroduced in iOS 12.4. Thanks, Apple!