Locking the collection or database during any modification of the critical section should follow this pattern:

• S mode to block writes (catch-up phase)
• X mode to block reads (promote phase)
• None (or IX) to releasing the critical section

Currently, exiting the critical section requires acquiring the collection/database lock in MODE_X.

This ticket proposes reducing that to MODE_IX, as there is no need for such a restrictive lock at that stage. When the critical section is already entered (i.e., reads/writes are blocked), it's sufficient to acquire only the CSS/DSS mutex to exit the critical section.