We doubled Kafka's partition count to fix growing lag, and lag grew instead. Walk me through what a rebalance does to a group.

More partitions should mean more throughput, so why did the backlog deepen? Because rebalance behavior depends on the group protocol, and the way consumers divide work decides who pays for it.

Grounded in researched DevOps, SRE and platform engineering interview loops, written to a senior-engineer editorial bar, and never padded to hit a word count.