In the past, digital copies books at the internet archive that were still under copyright were treated somewhat like real physical books. IA would let people "check out" an ebook for a limited time period. The number of checkouts was limited by the number of physical copies of the book that IA or IA-affiliates (or I think even just individuals who pinky promised that they owned a copy of the book whose PDF they were uploading) had in their possession.

At the beginning of COVID, they started doing what they called the "National Emergency Library" (this is probably the best term to look up to find more articles and different takes on the topic), where they just let everyone download copies of Harry_Potter.epub. IMO this was a needless provocation and not surprisingly book publishers claim that this is copyright infringement. They're going a bit scorched earth in response- the lawsuit isn't limited to just the "uncontrolled lending" aspect of the program.