This is a function of priority: it is saying that existing features working perfectly are more important than new features. It also should come with a culture

This is a function of priority: it is saying that existing features working perfectly are more important than new features. It also should come with a culture of treating bugs like you do a production incident: You do retrospectives and figure out what you can change to your process to reduce the likelihood of the same type of bug happening again. You likely also have a more extensive suite of tests to prevent regressions.