An administrator may have set the Max Bandwidth setting to a particular value in the Site Settings > Advanced Settings screen, and then notice that Zerto Virtual Replication is exceeding that bandwidth. This article explains the reason why this might occur.
The Max Bandwidth setting does not throttle Zerto Virtual Replication internal control or management traffic - it only throttles data traffic. If the environment is sufficiently large (in terms of VMs, hosts, and volumes), then the management server may require some additional network resources to synchronize the reflections between them. In any case, this "burst" should not be expected to be sustained.