Kawkab Express: parcel tracking has shown nothing since 03:10, the mobile app works

Kawkab Express (a fictional courier and parcel delivery company headquartered in Tangier) has two applications on the same RDS for PostgreSQL Multi-AZ database kawkab-suivi-prod:

• the couriers' mobile API (ECS), a recent one;
• the tracking portal suivi.kawkabexpress.ma, a legacy application installed by hand on the EC2 instance kawkab-suivi-01 during the migration to AWS two years ago.

Since 03:10, the portal has been showing “Tracking service unavailable”. The couriers, however, are scanning their parcels without any problem. Customer service opens at 08:00 and partner e-merchants are starting to call.

You are a production engineer, on the bastion with the AWS CLI v2 (region eu-west-1) and SSM permissions on kawkab-suivi-01 (i-0c3a5e7b9d1f24680).