for deamonset copy only spec.config not entore deepcopy

.chloggen/issue-4481.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. collector, target allocator, auto-instrumentation, opamp, github action)
+component: opamp
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note:  "OpAMP Bridge: collector.DeepCopy() causes full spec updates → DaemonSet mode fails (should patch spec.config only)"
+
+# One or more tracking issues related to the change
+issues: [https://github.com/open-telemetry/opentelemetry-operator/pull/4482]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

cmd/operator-opamp-bridge/internal/operator/client.go

@@ -102,9 +102,21 @@ func (c Client) Apply(name string, namespace string, configmap *protobufs.AgentC
 	if instance == nil {
 		return c.create(ctx, name, namespace, updatedCollector)
 	}
+
+
+	if instance.Spec.Mode == v1beta1.ModeDaemonSet {
+       return c.updateConfigOnly(ctx, instance, updatedCollector)
+	}
 	return c.update(ctx, instance, updatedCollector)
 }
 
+// patch ONLY spec.config on an existing CR
+func (c Client) updateConfigOnly(ctx context.Context, existing *v1beta1.OpenTelemetryCollector, desired *v1beta1.OpenTelemetryCollector) error {
+	base := existing.DeepCopy()               
+	existing.Spec.Config = desired.Spec.Config   // only mutate spec.config
+	return c.k8sClient.Patch(ctx, existing, client.MergeFrom(base))
+}
+
 func (c Client) validateComponents(collectorConfig *v1beta1.Config) error {
 	if len(c.componentsAllowed) == 0 {
 		return nil