Confusion about roles of Gitlab k8s agent and Flux for the manifests deployment

(not sure my question belongs here)

Hi there and happy new year

I’ve read page GitOps with GitLab: What you need to know about the Flux CD integration page Tutorial: Set up Flux for GitOps | GitLab, page Using GitOps with a Kubernetes cluster | GitLab and I viewed the 2 youtube videos that explain how to setup flux on gitlab but I’m failing to understand what brings adding the agentk to a kubernetes cluster. The video does not mention the installation of the gitlab kubernetes agent.
I’m also confused because in the past (about 1 year ago), I’ve tested gitlab agent for kubernetes to deploy manifests in a namespace, it was almost doing the same job.

Even after having played a couple with flux in gitlab, I don’t understand the benefits.

Can someone clarify all what the role of these components ? Iis gitlab k8s agent still necessary ?