Flow variables scope
Under Flow Engine context, all flow variables (both custom and special) defined for the flow instance, go out of scope when the flow instance completes execution. It does not affect the flow variables of the other instance.
Under non-flow engine context, for example, running a map under HCL API, using flow library functions in the map rules, all flow variables defined with the mapping functions go out of scope when the top map finishes execution. All flow variables defined are visible with top and RUN maps of the map. Each map instance execution gets its own set of flow variables and no two map instances share the same set of the variables.