We support the direct writes to transaction table, "config.transactions", to provide the maintenance ability to Support team. However, transactions use the transaction table for persistency as well. Changing its content arbitrarily may corrupt the data on the node and across the cluster. Thus we should ban direct writes to the transaction table in a replset. There's no restriction for writes to "config.transactions" in standalone mode. Support team can still restart the node in standalone mode, fix its content and restart as a replica, whenever that's necessary.

This work should also remove the session invalidation in OpObserver for direct writes on transaction table.