Make no mistake, it's not only that the capitalists in the states can't compete and want it gone, it's that they can't control the message. Musk owns twitter and it's lurched to the right, Facebook burying any Gaza data, the algorithm at alphabet is going to insure pro genocide propaganda gets top rank page position. But tiktok? It's a loose Cannon and that is why they are shutting it down. Don't believe they won't come after the lemmyverse next y'all. Spreading 'enemy disinformation' by sharing photos of dismembered Palestinian children. It is an information war and we are on the front lines.
Not aware of any though I'm sure there is one, just probably not that huge in scope at the moment. /c/datahoarder might know something of this or be of use. Maybe the reddit version since it tends to have more people.
Unfortunately social media apps like tik tok go out of their way to make it difficult to download and locally store anything you see on them. It's against their interests to let you take content off their platform. There are obviously modified APKs and non-mobile apps as well as websites that allow it but it's generally an annoying process. I'm sure some amount of it is being saved but in the way people browse these things and discover this content via algorithm it's kind of something you then have to go back to on another device to save and download and that's time-consuming and annoying so most people won't do that, or will tire of it after doing so for a bit.
The best hope is that there's some non-profit scraping this, that a couple of people have a day job grabbing and archiving this stuff in an attributable way so that it can be used in future though it's a big job and I'm honestly doubtful this is actually happening given it would seem to have no point. South Africa has presented their case of genocide, that's proceeding but the courts of public opinion are already set for now. You either see it for what it is (a genocide), you believe the zionist propaganda narrative, or you're just checked out. Re-presenting a tranche of videos of this stuff in 5 years would seem to be of little practical value. Either South Africa succeeds with their case in which case additional evidence is moot or they fail in which case it's not going to be reconsidered with a bunch of years old content the provenance of which cannot be proven beyond a shadow of a doubt given its original sources are now gone. It'd be useful for propaganda purposes but to who and where would you spread this when you're only archiving it because it's going to be removed and the platforms its been posted on locked down against the spread of that stuff in future.
Just the same I am sure some amount of it, a fraction is being archived in this way by some group but they may be academics or uninterested in sharing it further for now.