Archive has been around for well over a decade with no issues outside of sporadic DMCA claims against user uploaded content. For many many years they have been left alone, despite hosting a shit ton of copyrighted material.
Occasional legal battles that they've handled with no problems with the help of the EFF. This is the first "existential threat" to them in quite a long time.
This is absolutely because they pulled the emergency library stunt, and they were loud as hell about it. They literally broke the law and shouted about it.
Libraries are allowed to scan/digitize books they own physically. They are only allowed to lend out as many as they physically own though. Archive knew this and allowed infinite "lend outs". They even openly acknowledged that this was against the law in their announcement post when they did this.
I can absolutely say this is their own damn fault while disagreeing with the law they broke. There, I just did.