Cambridge Analytica happened with an app hosted on Facebook. This is hosted on your browser. So it’s not exactly how Cambridge Analytica happened because the trust model is completely different.
This collection can happen manually, within the users’ regular and fully authorized use, without facebooks involvement, and in fact without any ability for them to figure out that it happens.
That it happens through a browser extension (which they may or may not be technically able to detect) should not change legality or legitimacy.