Bitnami no longer offers the free PostgreSQL Docker image:
bitnami/charts#35164
Since the "calcom-stack" Helm chart relies on the Bitnami PostgreSQL Helm chart as a dependency, this leads to an image pull error for the Postgres StatefulSet deployment when using this chart.
Patching the image path of the Bitnami Helm chart does not seem to be sufficient, since several paths were modified in the Bitnami version of the Docker image. I would therefore recommend abandoning the Bitnami Helm chart and instead using the standard Postgres Docker image by including it directly in the root Helm chart (calcom-stack) as a deployment.