Hackers stole several archived mini discs from Thom Yorke, the band’s lead singer and main songwriter. The hackers asked for a $150,000 ransom to not release the mini disc archive. Radiohead decided to release all the 18 hours of stolen content themselves to benefit charity and put them up for sale on Bandcamp with all the proceeds to go to Extinction Rebellion. The entire archive of tracks has a size of 1.8GB in size and, after purchase, Radiohead will get access to online streaming via the Bandcamp app and can also download them all in MP3, FLAC and more audio formats.
Source: https://www.bleepingcomputer.com/news/security/radiohead-releases-ok-computer-sessions-after-hack-wont-pay-ransom/