Cannot access GCP VM from browser via <public_ip_address>: despite firewall rules are set.

Running my app docker image on VM instance Ubuntu 20.04 (focal) running on GCP, ports 0.0.0.0:3000 -> 3000/tcp (I am now using GCP free trial).

In firewall rules using network tags used : http-server, https-server, my-app. I have tried also without tags and applied to all. Priority is the highest. Network is by default. Direction is ingress. Action on match: allow. I was adding my

VM is pingable from other machine via its public IP and accessible from SSH.

How can I solve this issue of non-accessability?