This article explains that an MNHA node will go offline and show a HW error if the "CB Fabric Throughput Decreased" error is present.

root@Node0> show chassis high-availability information 
Node failure codes:
HW Hardware monitoring LB Loopback monitoring
MB Mbuf monitoring SP SPU monitoring
CS Cold Sync monitoring SU Software Upgrade

Node Status: OFFLINE [ HW ]
Local-id: 1
Local-IP: 198.224.48.105
HA Peer Information:

Peer Id: 2 IP address: 198.224.48.106 Interface: xe-1/0/11.0
Routing Instance: default
Encrypted: NO Conn State: UP
Cold Sync Status: COMPLETE

Services Redundancy Group: 0
Current State: ONLINE
Peer Information:
Peer Id: 2

SRG failure event codes:
BF BFD monitoring
IP IP monitoring
IF Interface monitoring
CP Control Plane monitoring

Services Redundancy Group: 1
Deployment Type: ROUTING
Status: INELIGIBLE
Activeness Priority: 0
Preemption: DISABLED
Process Packet In Backup State: NO
Control Plane State: N/A
System Integrity Check: COMPLETE
Failure Events: NONE
Peer Information:
Peer Id: 2
Status : INELIGIBLE
Health Status: UNHEALTHY
Failover Readiness: N/A

MNHA Node offline

SRG1 Ineligible

HW error

The MNHA node would go offline and show an Hardware error if the below alarm is present.  This alarm is generated when the number of fabric cards is less that the minimum requirements, thereby putting both the MNHA nodes into offline state.

root@Node0> show chassis alarms

10 alarms currently active

Alarm time        Class Description

2025-03-10 11:49:01 IST Minor CB Fabric Throughput Decreased

Check the device hardware to confirm the number of fabric cards installed.

The below kb gives information on the minimum requirements for the usage of SCB4  cards in SRX5600 and SRX5800.

https://supportportal.juniper.net/s/article/Operational-requirements-for-the-Usage-of-SCB4-in-SRX5k-chassis?language=en_US