Deploying my .net core webapp via private registry fails a few times before succeeding?

The attached deployment script works, but the website is broken for a bit while this fails a few times:

2020-11-03T08:31:46.056Z ERROR - Image pull failed: Verify docker image configuration and credentials (if using private repository)
2020-11-03T08:31:46.058Z INFO - Stopping site aed-synthetics because it failed during startup.
2020-11-03T08:31:49.526Z INFO - Pulling image from Docker hub: aedsyntheticsacr.azurecr.io/syntheticsdemo:latest
2020-11-03T08:31:49.592Z ERROR - DockerApiException: Docker API responded with status code=InternalServerError, response={"message":"Get https://aedsyntheticsacr.azurecr.io/v2/syntheticsdemo/manifests/latest: unauthorized: authentication required, visit https://aka.ms/acr/authorization for more information."}

Eventually about 5 minutes later it tries again and succeeds:

2020-11-03T08:31:49.608Z INFO - Stopping site aed-synthetics because it failed during startup.
2020-11-03T08:34:20.005Z INFO - Pulling image: aedsyntheticsacr.azurecr.io/syntheticsdemo:latest
2020-11-03T08:34:20.639Z INFO - latest Pulling from syntheticsdemo
2020-11-03T08:34:20.656Z INFO - bb79b6b2107f Pulling fs layer
...

Then the website is up, but why is this, is there some status I should check on the private container registry before trying to create the web app ?

Attached is my deployment script.37151-deploy.txt