Question

A downstream auth dependency starts returning slow 503s for ~5% of calls (a partial brownout, not down). Within minutes your fleet's outbound request rate to it **quadruples** and the dependency tips fully over, then your own API saturates too — load on the dependency is now far higher than the 5% that originally failed. CPU on your nodes is high but mostly in waiting/retrying. There was no traffic spike from users and no deploy. The dependency owner blames you for 'hammering' them. Who's right, and how do you triage and stop the cascade?