While the Change History cleanup task is running, you may have noticed a number of Events being generated for ARS stating:
Administrative Policy returned an error. Transaction (Process ID 65) was deadlocked on lock | communication buffer resources with another process and has been chosen as the deadlock victim. Rerun the transaction.
Product design. The appearance of these "deadlock victim" events depend on the amount of data in SQL: more data, the higher the probability of events like those being generated. But since ARS uses lower deadlock priority for scheduled tasks, in comparison to the ARS code, this should not affect the ARS operation. The schedule task will eventually complete without the deadlock.
An enhancement request (TF0490382) has been created detailing the feature: Redesign ARS SQL related tasks to avoid deadlocks while running Change History cleanup task.
The product team will evaluate the request and this feature may become available on a future release of the product.