BF-40247 produced a test failure in which a delete operation to remove documents from a timeseries buckets collection failed with error Collection did not exist at the beginning of operation but has subsequently been created as a time-series collection.
The test in question (jstests/concurrency/fsm_workloads/timeseries/timeseries_mixed_operations.js) creates the timeseries collection during its setup function, so the collection should always be present.
I cannot find another explanation for the test failure other than that the test does not wait for the replication to have caught up after the collection creation.
We should add a cluster.awaitReplication(); call after the collection creation to rule out the possibility of this being the reason for the test failure.