According to a poster on 4chan, a 558GB bundle of files doing the rounds on filesharing sites contains the complete source code for Watch Dogs Legion. They followed up the claim with several screenshots of the archive's file structure, and in October a ransomware gang did threaten to leak the source code. Just maybe the game about hackers has been hacked. If it's true, then those 558GB presumably include a lot of uncompressed assets as well as complete audio from various localizations and maybe more besides.
With access to the complete source code, modders could be able to tweak Watch Dogs Legion more than they otherwise would, and pirates may have an easier time cracking it. More significantly from an archival perspective, game historians would find it of value as well. When the 'gigaleak' of Nintendo source code and internal documents was released into the wilds earlier this year it proved to be a treasure trove of information of interest to die-hards.
Some players of Watch Dogs Legion are currently experiencing a corrupted save problem, and Ubisoft have said a fix for it may be several days away.