At some point someone optimizes the system to a global company-wide incrementing 128 bit counter. Instead of needing a costly database lookup against a growing database the microservice just fetches the current counter, increments it by one and hands out the new value. Easy, fast O(1) operation.

This even allows you to shard the service to provide high availability and distribute the service globally to reduce latency. Just give each instance a dedicated id range it can hand out. I'd suggest reserving some of the high bits to indicate data center id, and a couple more bits for id-generator instance within that dc.

Wait a second, this starts to look familiar ... does Twitter still do that, or did they eventually switch?