diff --git a/server/cluster/cluster.go b/server/cluster/cluster.go
index 20ea200491d..b1a7a6aa70b 100644
--- a/server/cluster/cluster.go
+++ b/server/cluster/cluster.go
@@ -889,7 +889,7 @@ func (c *RaftCluster) processRegionHeartbeat(region *core.RegionInfo) error {
 			if c.regionStats != nil {
 				c.regionStats.ClearDefunctRegion(item.GetID())
 			}
-			c.labelLevelStats.ClearDefunctRegion(item.GetID())
+			c.labelLevelStats.MarkDefunctRegion(item.GetID())
 		}
 		regionUpdateCacheEventCounter.Inc()
 	}
@@ -1969,6 +1969,7 @@ func (c *RaftCluster) updateRegionsLabelLevelStats(regions []*core.RegionInfo) {
 	for _, region := range regions {
 		c.labelLevelStats.Observe(region, c.getStoresWithoutLabelLocked(region, core.EngineKey, core.EngineTiFlash), c.opt.GetLocationLabels())
 	}
+	c.labelLevelStats.ClearDefunctRegions()
 }
 
 func (c *RaftCluster) getRegionStoresLocked(region *core.RegionInfo) []*core.StoreInfo {
diff --git a/server/cluster/cluster_test.go b/server/cluster/cluster_test.go
index f3365b1665e..255b1e2b547 100644
--- a/server/cluster/cluster_test.go
+++ b/server/cluster/cluster_test.go
@@ -1082,6 +1082,7 @@ func TestRegionLabelIsolationLevel(t *testing.T) {
 	opt.SetReplicationConfig(cfg)
 	re.NoError(err)
 	cluster := newTestRaftCluster(ctx, mockid.NewIDAllocator(), opt, storage.NewStorageWithMemoryBackend(), core.NewBasicCluster())
+	cluster.coordinator = newCoordinator(ctx, cluster, nil)
 
 	for i := uint64(1); i <= 4; i++ {
 		var labels []*metapb.StoreLabel
@@ -1116,13 +1117,42 @@ func TestRegionLabelIsolationLevel(t *testing.T) {
 		StartKey: []byte{byte(1)},
 		EndKey:   []byte{byte(2)},
 	}
-	r := core.NewRegionInfo(region, peers[0])
-	re.NoError(cluster.putRegion(r))
+	r1 := core.NewRegionInfo(region, peers[0])
+	re.NoError(cluster.putRegion(r1))
 
-	cluster.updateRegionsLabelLevelStats([]*core.RegionInfo{r})
+	cluster.updateRegionsLabelLevelStats([]*core.RegionInfo{r1})
 	counter := cluster.labelLevelStats.GetLabelCounter()
 	re.Equal(0, counter["none"])
 	re.Equal(1, counter["zone"])
+
+	region = &metapb.Region{
+		Id:       10,
+		Peers:    peers,
+		StartKey: []byte{byte(2)},
+		EndKey:   []byte{byte(3)},
+	}
+	r2 := core.NewRegionInfo(region, peers[0])
+	re.NoError(cluster.putRegion(r2))
+
+	cluster.updateRegionsLabelLevelStats([]*core.RegionInfo{r2})
+	counter = cluster.labelLevelStats.GetLabelCounter()
+	re.Equal(0, counter["none"])
+	re.Equal(2, counter["zone"])
+
+	// issue: https://github.com/tikv/pd/issues/8700
+	// step1: heartbeat a overlap region, which is used to simulate the case that the region is merged.
+	// step2: update region 9 and region 10, which is used to simulate the case that patrol is triggered.
+	// We should only count region 9.
+	overlapRegion := r1.Clone(
+		core.WithStartKey(r1.GetStartKey()),
+		core.WithEndKey(r2.GetEndKey()),
+		core.WithLeader(r2.GetPeer(8)),
+	)
+	re.NoError(cluster.HandleRegionHeartbeat(overlapRegion))
+	cluster.updateRegionsLabelLevelStats([]*core.RegionInfo{r1, r2})
+	counter = cluster.labelLevelStats.GetLabelCounter()
+	re.Equal(0, counter["none"])
+	re.Equal(1, counter["zone"])
 }
 
 func heartbeatRegions(re *require.Assertions, cluster *RaftCluster, regions []*core.RegionInfo) {
diff --git a/server/statistics/region_collection.go b/server/statistics/region_collection.go
index 8d4d6d1849c..fa2889a7bd3 100644
--- a/server/statistics/region_collection.go
+++ b/server/statistics/region_collection.go
@@ -320,6 +320,7 @@ type LabelStatistics struct {
 	sync.RWMutex
 	regionLabelStats map[uint64]string
 	labelCounter     map[string]int
+	defunctRegions   map[uint64]struct{}
 }
 
 // NewLabelStatistics creates a new LabelStatistics.
@@ -327,6 +328,7 @@ func NewLabelStatistics() *LabelStatistics {
 	return &LabelStatistics{
 		regionLabelStats: make(map[uint64]string),
 		labelCounter:     make(map[string]int),
+		defunctRegions:   make(map[uint64]struct{}),
 	}
 }
 
@@ -360,14 +362,26 @@ func (l *LabelStatistics) Reset() {
 	regionLabelLevelGauge.Reset()
 }
 
-// ClearDefunctRegion is used to handle the overlap region.
-func (l *LabelStatistics) ClearDefunctRegion(regionID uint64) {
+// MarkDefunctRegion is used to handle the overlap region.
+// It is used to mark the region as defunct and remove it from the label statistics later.
+func (l *LabelStatistics) MarkDefunctRegion(regionID uint64) {
 	l.Lock()
 	defer l.Unlock()
-	if label, ok := l.regionLabelStats[regionID]; ok {
-		l.labelCounter[label]--
-		delete(l.regionLabelStats, regionID)
+	l.defunctRegions[regionID] = struct{}{}
+}
+
+// ClearDefunctRegions is used to handle the overlap region.
+// It is used to remove the defunct regions from the label statistics.
+func (l *LabelStatistics) ClearDefunctRegions() {
+	l.Lock()
+	defer l.Unlock()
+	for regionID := range l.defunctRegions {
+		if label, ok := l.regionLabelStats[regionID]; ok {
+			l.labelCounter[label]--
+			delete(l.regionLabelStats, regionID)
+		}
 	}
+	l.defunctRegions = make(map[uint64]struct{})
 }
 
 // GetLabelCounter is only used for tests.