Bash Script Can't Connect to Azure Postgres using ENV Vars - "The Username should be in <username@hostname> format"

I have a bash script that exports ENV vars to use in connecting to an Azure Postgres DB (mydb.postgres.database.azure.com). For the user portion of that specifically it looks like this: export PGUSER="postgres@mydb" This works fine to connect to my local DB where the @mydb part isn't required, but it fails when connecting to Azure (where it is required) with: > psql: FATAL: Invalid Username specified. Please check the Username and retry connection. The Username should be in format. I've found lots of solutions/answers to this like this one and this one however those aren't viable solutions when using ENV vars to set connection details (and while I didn't expect it to work I nonetheless tried changing my script to export PGUSER="postgres%40mydb" and indeed it did yield the same error). Does anyone know how to accomplish this?