Is it true, that we cannot have any service running port 80 or 443 , when we have traefik?

The Traefik ingress controller deploys a LoadBalancer Service that uses ports 80 and 443. By default, ServiceLB will expose these ports on all cluster members, meaning these ports will not be usable for other HostPort or NodePort pods.

https://docs.k3s.io/networking#traefik-ingress-controller

Thanks for the link