The Wayback Machine’s site has been breached, but its founder says the data is still there.
One concern I do have that's maybe worth considering is that The Wayback Machine is often used as an authoritative source of what a website was like at some point. Like, if you're citing information, it's considered appropriate to link to The Wayback Machine.
There are entities who would potentially be interested in being able to modify that authoritative history.
I don't think that that's likely an issue here -- someone who wanted to secretly modify the history probably wouldn't have also modified the site to indicate that it was compromised -- but the ability to modify such a representation might have a lot of potential room for abuse.
It might be worthwhile, if the infrastructure permits for it, to do some sort of storage mechanism that makes it hard to spoof old data.
If you're familiar with blockchains, they leverage a chain of hashes, so that there's a piece of data dependent on all prior entries. That sort of dependency didn't originate with blockchain -- the CBC cipher mode does the same thing, off the top of my head -- and I don't think that a fully-distributed mode of operation is required here.
However, it might be interesting to use some sort of verifiable storage format where hashes of checkpoints are distributed elsewhere, so that if someone does manage to get into The Internet Archive, they can't go fiddle with past things without it becoming visible.
Git repositories take advantage of this with their signed commits and hash trees.
If someone gets into The Internet Archive, they could potentially compromise a copy before it gets hashed (though if they supported the submitter signing commits, a la git, that'd avoid that for information that originated from somewhere other than The Internet Archive). This can't protect against that. But it can protect the integrity of information archived prior to the compromise, which could be rather important.