Our monitoring system detected a temporary service interruption, which resolved automatically.
The Azure West Europe region experienced a fiber cut (https://app.azure.com/h/YKS4-9PZ/14abab) which resulted in traffic between Availability zones to be disrupted. Our system was not fully resilient against this sort of outage, resulting in message loss during the time period from Sept 14 22:05 UTC to Sept 14 22:22 UTC.
A detailed postmortem analysis is available upon request