Definitely the biggest news this week. The takedown, titled "Operation Duck Hunt", is "the largest U.S.-led financial and technical disruption of a botnet infrastructure", according to the DOJ.
The botnet consisted of over 700,000 infected machines, 200,000 of them residing in the US. It was used as an initial infection vector by several ransomware groups like Conti, REvil and many more.
The FBI was able to redirect botnet traffic through servers controlled by them, which in turn instructed the machines to download a "patch" that uninstalled the malware. They were able to do this by first taking over the computer of one of the botnet admins, where they found files with chatlogs, payment information, and encryption keys that were used to communicate with the botnet. There's a great read on this in more detail here.
Over $8.6 million in crypto currency was also seized, which victims can apply to receive a portion of.
You can find the official announcement here, and watch the FBI Director himself announce the takedown on Youtube. People can check if their devices were infected through Have I been Pwned or through the Check your hack site from the Dutch police.