I think your answer is the most logical to me as a developer, we often miss simple things, the PM overlooks it, and so it goes into production this way. I don't

I think your answer is the most logical to me as a developer, we often miss simple things, the PM overlooks it, and so it goes into production this way. I don't think its malicious. Sometimes bugs just don't become obvious until things break. We have all found an unintended consequence of our code that had nothing wrong with it technically sooner or later.