Thanks for your patience.
As per my understanding you are facing some issue creating a PostgreSQL flexible server using terraform.
There is an outage going one for customers creating Azure PostgreSQL flexible server. Our product Group are actively working on it.
Existing servers are not impacted. Only PITR and new server creations are impacted.
You can track azure service outage using the link below.
https://status.azure.com/en-us/status
Thanks,
Shakti