This KB article explains one of the VRRP-related behaviors observed on the ACX5448 and ACX710 platforms.

On the ACX5448 and ACX710 platforms, when VRRP is configured on multiple logical interfaces under the same physical interface (IFD) or the same AE interface, and they share the same VRRP group ID, traffic loss may occur. This issue typically happens when one VRRP instance transitions to a state that differs from the others.
For example, this can occur when the configuration intentionally changes the priority so that one VRRP instance moves to the backup state while the others remain in the master state.
During such a VRRP state transition, the VRRP group and the VSI (Virtual System Identifier) associated with that group are removed from all IFLs under the same IFD (or AE).
As a result, all VRRP traffic is lost.

Diagram illustrating the issue 

– Initial state

  A                 |                     |
  |           +-----------+         +-----------+
  |           |  ACX5448  |         |  ACX5448  |
  |           |           |         |           |
  |           +-----------+         +-----------+
  |                 |                     |
  |  ae0.0 : master |                     | ae0.0 : backup
  |  ae0.1 : master |                     | ae0.1 : backup
  |  ae0.2 : master |     +---------+     | ae0.2 : backup
  |                 +-----[  Switch |-----+
  |                       +---------+
  +------------------------+   |    
Traffic for ae0.0          |   |

- Change the VRRP priority of ae0.1

Traffic for ae0.0
                    |                     |
              +-----------+         +-----------+
              |  ACX5448  |         |  ACX5448  |
              |           |         |           |
              +-----------+         +-----------+
  X                 |                     |
  A  ae0.0 : master |                     | ae0.0 : backup
  |  ae0.1 : backup |                     | ae0.1 : master
  |  ae0.2 : master |     +---------+     | ae0.2 : backup
  |                 +-----[  Switch |-----+
  |                       +---------+
  +------------------------+   |    
Traffic for ae0.0          |   |

This issue has been resolved in PR1897117.
The fix is available starting from the following release:
Junos: 25.4R1 or later

Workaround
Use an IRB (Integrated Routing and Bridging) interface instead of a physical(IFD) or AE interface, or use a different VRRP group ID.