Kubernetes Demo- Deployment- Update and Rollback

In the last section when deliberately an error image was edited what was the math behind pods.
Why did it deleted just 1 image and deployed 3 new pods before stopping? Once replacing the older pods shouldn’t it stop once a single pod is in error(imagepullbackoff)?

Hello ayush,
Please check this lecture https://www.udemy.com/course/learn-kubernetes/learn/lecture/9723240 to understand the deployment strategies. and the difference between recreate and rolling update. I hope this lecture help you.