While that might be true in some edge cases, most of the content they archive is either no longer distributed through any legal means (e.g. original 78rpm discs) or copyright doesn’t even apply (e.g. recipes).
And the digital book program been operating for a long time as a digital library, but Internet Archive decided to remove some restrictions during the pandemic to allow students to access materials needed for their studies and of course copyright trolls jumped on a chance to fuck everyone over.
While claims are legitimate in a most broad sense, they are completely baseless from the intent of copyright. You need a profit motive for copyright to be considered infringement and in neither of these cases it exists.