SERVER-138623 could have been caught if there were resharding with zones JS tests that induced stepdowns of config primary. No JS test combines resharding, zones, and a config primary failover as I looked.

sharding_csrs_continuous_config_stepdown.yml excludes all reshard.js with (TODO SERVER-51495),

concurrency_sharded_stepdown_terminate_kill_primary_with_balancer_and_config_transitions_and_add_remove_shard.yml and concurrency_resharding_with_lightweight_stepdowns.yml does stepdown config server and runs resharding FSM tests like reshard_collection_crud_ops.js but without any zones.

We can either extend reshard_collection_crud_ops.js to also setup zones or add a new sibling test with zones and verify they exist in config.tags after reshardCollection completes including the case with forceRedistribution: true on pre-existing zones.