There have been a number of articles (pop and scholarly) about malicious code being social engineered into codebases over the past few years. And, in this case, the malice is “expected” from one of the long time developers to begin with.
Also: We got INCREDIBLY lucky that Andres Freund detected it when he did. Because that was hitting right around the time a lot of the major distros were preparing their major releases (Fedora basically escaped by the skin of their teeth).
Malicious manipulation of open source projects has always been a concern. And the vast majority of us do the equivalent of signing whatever form we are given because “oh it just looks like a standard contract”.