Can anyone here please share some steps or best practice in how to rectify the issue where Backup Repository is the source of the backup problem like in the below screenshot:

I have just upgraded my Veeam into 9.5 Update 1 (Veeam Backup & Replication 9.5.0.823), and then this problem started to happen.
Note:
The backup server is running Windows 2012 R2 Std as VM.
vNIC 2 - iSCSI LUN 1 Windows Guest iSCSI initiator - Y:\ 30 TB NTFS drive (RAID 6) on QNAP TS-EC1280u
vNIC 3 - iSCSI LUN 2 Windows Guest iSCSI initiator - Z:\ 30 TB NTFS drive (RAID 6) on QNAP TS-EC1280u
iSCSI link speed is 10 Gbps.