What don’t you understand? Those websites that defame a company are liable for that defamation. In this case Google defamed a company in its AI summary and is this liable for that defamation.
but if Wikipedia itself writes harmful content such as encouraging people to drink bleach, then wikipedia is liable. Google now generates its own content with AI, that defame others, so Google is liable.
And those tons of websites are liable for their misinformation. It's probably not worth suing some random blog because the author probably doesn't have money or lives in Russia. But Google has lots of money and a legal presence in almost every jurisdiction.
It's why people say "Donald Trump was held civilly liable for sexual assault in the E Jean Carroll case" instead of "Donald Trump raped E Jean Carroll"