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.
There were some textbooks (almost exclusively college level ones), but they were located at the bottom of the page below the bodice-ripper "Romance" category. The unrestricted lending wasn't limited to certain categories or anything like that.
But Internet Archive quite clearly and blatantly broke law - in situation where their operation were already on edge.
So there is no surprise at all that various entities used this occasion to sue them. Hopefully IA will survive, but I am not impressed by their strategy.