This article introduces the support capability of the packet-based processing mode in SRX cluster environment
Both packet-based processing and selective stateless packet-based services are supported in SRX chassis cluster environment, same as the standalone devices.
Please refer to KB30461 [juniper.net] with details on how to change the traffic mode from flow mode to traffic mode.
For other features which are supported or not supported on SRX cluster devices, please refer to the guide below:
Chassis Cluster Features Supported on SRX Series Devices | Junos OS | Juniper Networks
https://supportportal.juniper.net/s/article/SRX-How-to-change-forwarding-mode-for-IPv4-from-flow-based-to-packet-based