I don’t think that’s a fair assessment. It’s a cache. Is Cloudflare liable for hosting lib genesis then? Because cliudflare caches much worse stuff than copyrighted pictures and books.
There’s a lot to talk about but afaik Section 230 that defines every website in US says that host is not responsible for user content and I honestly don’t see how big copyright could prosecute lemmy.world here that’s not even hosting data directly.