diff --git a/cmd/sing-box/cmd.go b/cmd/sing-box/cmd.go
index 9ae3a268..a2d4a00b 100644
--- a/cmd/sing-box/cmd.go
+++ b/cmd/sing-box/cmd.go
@@ -67,5 +67,5 @@ func preRun(cmd *cobra.Command, args []string) {
 	if len(configPaths) == 0 && len(configDirectories) == 0 {
 		configPaths = append(configPaths, "config.json")
 	}
-	globalCtx = service.ContextWith(globalCtx, deprecated.NewEnvManager(log.StdLogger()))
+	globalCtx = service.ContextWith(globalCtx, deprecated.NewStderrManager(log.StdLogger()))
 }
diff --git a/cmd/sing-box/cmd_check.go b/cmd/sing-box/cmd_check.go
index 1beab954..29a39081 100644
--- a/cmd/sing-box/cmd_check.go
+++ b/cmd/sing-box/cmd_check.go
@@ -30,7 +30,7 @@ func check() error {
 	if err != nil {
 		return err
 	}
-	ctx, cancel := context.WithCancel(context.Background())
+	ctx, cancel := context.WithCancel(globalCtx)
 	instance, err := box.New(box.Options{
 		Context: ctx,
 		Options: options,
diff --git a/experimental/deprecated/env.go b/experimental/deprecated/stderr.go
similarity index 59%
rename from experimental/deprecated/env.go
rename to experimental/deprecated/stderr.go
index 113b8717..0826baf9 100644
--- a/experimental/deprecated/env.go
+++ b/experimental/deprecated/stderr.go
@@ -7,15 +7,23 @@ import (
 	"github.com/sagernet/sing/common/logger"
 )
 
-type envManager struct {
-	logger logger.Logger
+type stderrManager struct {
+	logger   logger.Logger
+	reported map[string]bool
 }
 
-func NewEnvManager(logger logger.Logger) Manager {
-	return &envManager{logger: logger}
+func NewStderrManager(logger logger.Logger) Manager {
+	return &stderrManager{
+		logger:   logger,
+		reported: make(map[string]bool),
+	}
 }
 
-func (f *envManager) ReportDeprecated(feature Note) {
+func (f *stderrManager) ReportDeprecated(feature Note) {
+	if f.reported[feature.Name] {
+		return
+	}
+	f.reported[feature.Name] = true
 	if !feature.Impending() {
 		f.logger.Warn(feature.MessageWithLink())
 		return
diff --git a/experimental/libbox/deprecated.go b/experimental/libbox/deprecated.go
index b953014f..f85b7747 100644
--- a/experimental/libbox/deprecated.go
+++ b/experimental/libbox/deprecated.go
@@ -4,27 +4,28 @@ import (
 	"sync"
 
 	"github.com/sagernet/sing-box/experimental/deprecated"
+	"github.com/sagernet/sing/common"
 )
 
 var _ deprecated.Manager = (*deprecatedManager)(nil)
 
 type deprecatedManager struct {
-	access   sync.Mutex
-	features []deprecated.Note
+	access sync.Mutex
+	notes  []deprecated.Note
 }
 
 func (m *deprecatedManager) ReportDeprecated(feature deprecated.Note) {
 	m.access.Lock()
 	defer m.access.Unlock()
-	m.features = append(m.features, feature)
+	m.notes = common.Uniq(append(m.notes, feature))
 }
 
 func (m *deprecatedManager) Get() []deprecated.Note {
 	m.access.Lock()
 	defer m.access.Unlock()
-	features := m.features
-	m.features = nil
-	return features
+	notes := m.notes
+	m.notes = nil
+	return notes
 }
 
 var _ = deprecated.Note(DeprecatedNote{})