The inclusion of copyright characters will be a huge deal IMHO, and Meta as the creator within a product that provides them commercial gain will likely not be able to claim fair use.
The technical challenges of cleaning up their data set to images that are legally safe will be interesting, but it also means that their training set includes lots of copyright imagery already. Which will mean that they're potentially open for even more legal headaches
Even more interesting is how they’d need to filter out studio specific depictions. E.g rapunzel is public domain but not Disneys depiction.
That’s before you get into individual artist rights as well, but at thethe corporation level this is fascinating