On a brand new cluster, the config.collections collection on the configsvr is currently implicitly created when sharding the very first collection. There is a situation where attempting to refresh the CatalogCache (which does a Snapshot read on config.collections) from a CSRS node that has:
i) replicated the implicit creation of config.collections
ii) but not advanced its majority commit point to be inclusive of it
can fail with SnapshotUnavailable.
This situation will eventually resolve once the CSRS secondaries advance their majority commit point past the creation of config.collections.

To avoid this situation, we should make sure that config.collections exists upon configsvr startup.