Did you have a common, centralized data store or did each and every microservice manage their own instance?
(Because this is at the same time one of the defining elements of this architecture... and the first one to be opted out when you actually start using it "for real").
Yes and no. The "central" part of data flowed naturally through services (i.e. passed in requests and webhooks, not in responses). Microservices maintained local state as well, though it was mostly small and disposable due to whole-intra crashonly design. For example, we didn't hesitate to shut something down or hot-fix it, except for bus-factor periods when there's only few of them. They could also go down by themselves or by upstream, and routers avoided them automatically.
(Because this is at the same time one of the defining elements of this architecture... and the first one to be opted out when you actually start using it "for real").