It is right as Docker Compose prefixes services with the project name and adds a replica number as suffix so frontend is not a container but a composer service and the container is probably something like yourproject-frontend-1
Regarding the issue, if the container is actually running, execute the health check manually and see what it returns without -f.
What CMD? ENTRYPOINT and CMD is responsible for what wil run in the container. If you run curl in CMD, you will not have the server. Although your error message proves it is not running now either or constantly restarts and you managed to access it at the right time in the browser.