According to my research, the dual-hat agreement has existed between USCYBERCOM and the NSA ever since CYBERCOM’s inception in 2010. The arrangement itself is about one person leading both organizations and while it was initially for saving costs and was a temporary solution, it has remained in place ever since. However, even with the conversation of a split in 2016, as of September of 2023, the organizations haven’t split. While Congress gave them metrics in 2016 to work toward a split, there are multiple reasons why rushing it isn’t as beneficial. According to Senator Mike Rounds, a split or a lack of the arrangement would “have two separate bureaucracies who would clash on a daily basis about the use of the tools, about the coordination of efforts, about the protection of their own silos.” Furthermore, splitting both organizations would result in more costs, slower decision-making, and lots of time being invested into restructuring the organizations to work separately and train people for that leadership position. The organizations have also helped with their complementary goals, quicker decision-making to prevent cyber-attacks, and have even maintained efficient security with elections and partner nations. But, even with the amount of work done with the dual-hat arrangement, the plan for CYBERCOM is to split from the NSA eventually, but it will most likely be a long time before that happens.

https://securityintelligence.com/articles/why-keep-cybercom-and-nsas-dual-hat-arrangement/

https://fedscoop.com/cyber-command-and-nsa-still-working-to-meet-measures-necessary-to-split/