Application deletion by applicationSet when using ApplicationSet Policy or syncPolicy.applicationsSync

[flickers]

Summary

There is no way to see (in UI or in the argocd application CR) when an application generated from an applicationSet is no longer generated from said applicationSet when using applicationsSync create-update or create-only like is described in Managed Applications modification Policies.
Discussion on slack found there https://cloud-native.slack.com/archives/C01TSERG0KZ/p1692707246420029

Motivation

It is likely that this only applies when the applicationSet no longer generates an application. My use-case is that I would want to add an extra fail-safe to prevent deletion of applications even though we have branch protection in git to make sure that doesn't happen.
I would like to use syncPolicy.applicationsSync: create-update in applicationSets to prevent accidental deletion of applications in production clusters but would like ArgoCD to still show somehow the drift from desired state.

Proposal

For applications no longer generated from the applicationSets and you have syncPolicy.applicationsSync: create-update or syncPolicy.applicationsSync: create-only defined on the applicationSet level or if you have the controller parameters --policy create-update or --policy create-only set.
Produce some kind of status, label or any indicator (in the UI and in the argocd application CR) that the application is no longer being generated by the applicationSet generator.
Users of ArgoCD would then be able to fix the desired state (git in my case) if there was an accidental change/deletion or remove the application from cluster(s) if this application should indeed be deleted.

[CaMoPeZzz]

I always face this problem when moving an application to another cluster (using Cluster generator). As a result, the application remains in the old cluster and does not differ in UI from the new one.