Try this

clusters/pi_cluster/cloudflare.yaml

@@ -4,10 +4,6 @@ metadata:
   name: cloudflare
   namespace: flux-system
 spec:
-  decryption:
-    provider: sops
-    secretRef:
-      name: sops-age
   interval: 60s
   sourceRef:
     kind: GitRepository

infrastructure/cloudflare/kustomization.yaml

@@ -3,6 +3,11 @@ kind: Kustomization
 metadata:
   labelsname: cloudflare
   namespace: cloudflare
+spec:
+  decryption:
+    provider: sops
+    secretRef:
+      name: sops-age
 resources:
 - namespace.yaml
 - secrets.yaml