Upgrading from v2.x.x to v4.x.x

🏬Self-hosted❓Question❌Unsolved

I have self hosted zitadel v2.x.x on k8s using helm chart v8. We have built our own Custom Login UI. Now I want to upgrade it to the new stable version v4.x.x. I have gone through the necessary migration guide. Just want to know is it mandatory to deploy the new v2 login UI or can I disable it and use the default zitadel login as I already have custom ui for my platform which proxies zitadel?