Currently, we provide a server parameter (ttlMonitorEnabled) that can be configured at startup or runtime to enable or disable the TTL monitor. However, disabling this parameter also affects internal collections, such as the config.system.sessions collection.

This is problematic because disabling the TTL monitor for an extended period can lead to unbounded growth of the config.system.sessions collection. Eventually, this may prevent the creation of new sessions due to reaching the limit on active logical sessions.

To address this, we should implement a mechanism—such as a new server parameter—that disables the TTL monitor for user collections only, while allowing the TTL monitor to continue operating on internal collections.