SERVER-81293 committed some changes to jstests that have turned out wrong because enableSharding is called with the primaryShard option right after creating a collection, that implicitly creates a database potentially on a shard different than the desired one.

We have observed some sporadic failures only in multiversion suites with mixed binaries (random binaries versions for each shard). When implicitly creating a database, the least loaded shard is chosen and most probably the issue is due to the fact that shards in older versions create less internal collections.