API Optimization Tale: Monitor, Fix and Deploy (on Friday)

I saw a green build on a Friday afternoon. I knew I need to push it to production before the weekend. My gut told me it was a trap. I had already stayed late to revert a broken deploy. I knew the risk. In the middle of a service extraction project, we decided to migrate from REST to GraphQL and optimize API usage. My deploy was a part of this radical change. Why was I deploying so late? How did we measure the migration effects? And why was I testing on production? I'll tell you a tale of small steps, monitoring, and old tricks in a new setting. Hope, despair, and broken production included.