The following query will consistently run versionless for the $unionWith sub-pipeline concerning $collstats against db.other.
This causes the the shard role to invariant since any catalog access must come with version, even if user collections are not involved.
Note that seem to only effect

• $collStats
• $listCatalog
  which mainly target metadata and statistics, not user data aggregation
  And the assertion is only present in tests, so this doesn't effect availability in production

db.main.aggregate([
{ $match: {_id: -1}},
{
   $unionWith: {
   coll: "other",
    pipeline: [{$collStats: {storageStats: {}, count: {}}}],
  },
 },
])