Filed after cloning SERVER-111657:
With the ObservableMutex feature enabled in SERVER-106634, we can now have greater observability into the cost of mutex contention. Please consider identifiing critical long-lived mutexes that could benefit from this feature and enabling them following this usage guide. This feature is already enabled for ServiceContext, ReplicationCoordinator, TransactionCoordinator, Grid, SessionManager, and ConnectionPool mutexes.

I think this makes sense for the query stats store metric. Particularly if we have changes in $queryStats traffic pattern from query shape insights or the like. Might also make sense within the rate limiting code.