Hello @ftapin,
There is a similar issue I tried to troubleshoot that might be interesting if you try to connect to a Cloud SQL and on which I suggest some debugging steps.
As Airbyte containers are started in host network mode so you should be able to use localhost instead of host.docker.internal.
Did you activate SSL on your docker postgres DB? I see this postgres?ssl=true&sslmode=require in your DATABASE_URL, your airbyte-db container might have SSL turned off.