Below are the optics that Customer had. As you can seen, router has Ports 0,4,5 and 9 as 400G ports.

FPC 3            REV 24   750-077003   BCEJ2507          FPC-JNP10003-MEZZ-A
  PIC 0                   BUILTIN      BUILTIN           4x400G/10x200G/20x100G
    Xcvr 0       XXXX     NON-JNPR     INLBTI660207      QSFP56-DD-400G-FR4
    Xcvr 1       0        NON-JNPR     INMBBB204968      QSFP-100GBASE-LR4
    Xcvr 4       XXXX     NON-JNPR     INLBTI660067      QSFP56-DD-400G-FR4
    Xcvr 5       XXXX     NON-JNPR     INLBTI660013      QSFP56-DD-400G-FR4
    Xcvr 6       0        NON-JNPR     INMBBB204964      QSFP-100GBASE-LR4
    Xcvr 8       0        NON-JNPR     INMBBB204791      QSFP-100GBASE-LR4
    Xcvr 9       XXXX     NON-JNPR     INLBTI660054      QSFP56-DD-400G-FR4
  PIC 1                   BUILTIN      BUILTIN           4x400G/10x200G/20x100G
    Xcvr 0       XXXX     NON-JNPR     INLBTI660083      QSFP56-DD-400G-FR4
    Xcvr 1       0        NON-JNPR     INMBBB204800      QSFP-100GBASE-LR4
    Xcvr 3       0        NON-JNPR     INMBBB203491      QSFP-100GBASE-LR4
    Xcvr 4       XXXX     NON-JNPR     INLBTI660080      QSFP56-DD-400G-FR4
    Xcvr 5       XXXX     NON-JNPR     INLBTI660085      QSFP56-DD-400G-FR4
    Xcvr 6       0        NON-JNPR     INMBBB204750      QSFP-100GBASE-LR4
    Xcvr 8       0        NON-JNPR     INMBBB204922      QSFP-100GBASE-LR4
    Xcvr 9       XXXX     NON-JNPR     INLBTI660220      QSFP56-DD-400G-FR4

As per Juniper documentation Per port group on Brackla can support 1Tb of speed. So, in above example - ports 0 to 4 on PIC0 form 1 port group and ports 5 to 9 form another port group on PIC1.

With this configuration, below alarms will be seen:

labroot@jtac-ptx10003-160c-r2004# run show chassis alarms
14 alarms currently active
Alarm time              Class Description
2023-11-24 09:39:24 IST Minor FPC-3 PIC-0: Invalid Port Speed Configuration
2023-11-24 09:39:24 IST Minor FPC-3 PIC-1: Invalid Port Speed Configuration

With QSFP56-DD transceivers, you can configure a data rate of 1x400 Gbps on the two outer ports in a port group. To attain the maximum 1 Tbps throughput, you can configure combinations of two ports of 1x400 Gbps and two ports of 1x100 Gbps data rates in a port group with the following limitations:

• Only the ports at the outer edge of each group can be configured for 1x400 Gbps (using QSFP56-DD transceivers).

• When ports 0, 4, 5, 9 are configured as 1x400 Gbps, the center ports 2 and 7 must be blank. You must configure the blank ports by using the set chassis fpc fpc-slot-number pic pic-slot-number port port-number unused command.
  
  For example:
   

  labroot@jtac-ptx10003-160c-r2004# set chassis fpc 3 pic 0 port 2 unused

  labroot@jtac-ptx10003-160c-r2004# set chassis fpc 3 pic 0 port 7 unused   

  labroot@jtac-ptx10003-160c-r2004# commit