Did they actually know it was a lie? E.g. https://www.nytimes.com/2021/10/10/opinion/instagram-faceboo...
After reading the NYT article it still seems to me that a more ethical company would have done more to address the probable issues. Meta did very little and seemed to cherrypick the most favourable public studies. Anyyway, all this doesn't seem suprising or even unusual to me. I generally don't think that we should expect companies to act very ethical. Rather, incentive structures should be created/amended in a way so that purely self interested companies act as if they were ethical.