diff --git a/quiche/common/quiche_feature_flags_list.h b/quiche/common/quiche_feature_flags_list.h
index 9d27ee1..eb4aecc 100755
--- a/quiche/common/quiche_feature_flags_list.h
+++ b/quiche/common/quiche_feature_flags_list.h
@@ -18,7 +18,6 @@
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_bbr2_probe_two_rounds, true, true, "When true, the BB2U copt causes BBR2 to wait two rounds with out draining the queue before exiting PROBE_UP and BB2S has the same effect in STARTUP.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_bbr2_simplify_inflight_hi, true, true, "When true, the BBHI copt causes QUIC BBRv2 to use a simpler algorithm for raising inflight_hi in PROBE_UP.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_block_until_settings_received_copt, true, true, "If enabled and a BSUS connection is received, blocks server connections until SETTINGS frame is received.")
-QUICHE_FLAG(bool, quiche_reloadable_flag_quic_can_send_ack_frequency, false, false, "If true, ack frequency frame can be sent from server to client.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_conservative_bursts, false, false, "If true, set burst token to 2 in cwnd bootstrapping experiment.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_conservative_cwnd_and_pacing_gains, false, false, "If true, uses conservative cwnd gain and pacing gain when cwnd gets bootstrapped.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_default_enable_5rto_blackhole_detection2, true, true, "If true, default-enable 5RTO blachole detection.")
diff --git a/quiche/quic/core/quic_connection.cc b/quiche/quic/core/quic_connection.cc
index 38f2996..7b40eda 100644
--- a/quiche/quic/core/quic_connection.cc
+++ b/quiche/quic/core/quic_connection.cc
@@ -3259,7 +3259,6 @@
           FirstSendingPacketNumber() + kMinReceivedBeforeAckDecimation;
 
   if (should_bundle_ack_frequency) {
-    QUIC_RELOADABLE_FLAG_COUNT_N(quic_can_send_ack_frequency, 3, 3);
     ack_frequency_sent_ = true;
     auto frame = sent_packet_manager_.GetUpdatedAckFrequencyFrame();
     visitor_->SendAckFrequency(frame);
@@ -4099,7 +4098,6 @@
   }
   if (send_ack_frequency_on_handshake_completion_ &&
       sent_packet_manager_.CanSendAckFrequency()) {
-    QUIC_RELOADABLE_FLAG_COUNT_N(quic_can_send_ack_frequency, 2, 3);
     auto ack_frequency_frame =
         sent_packet_manager_.GetUpdatedAckFrequencyFrame();
     // This AckFrequencyFrame is meant to only update the max_ack_delay. All
diff --git a/quiche/quic/core/quic_connection_test.cc b/quiche/quic/core/quic_connection_test.cc
index 74060c0..87e13dd 100644
--- a/quiche/quic/core/quic_connection_test.cc
+++ b/quiche/quic/core/quic_connection_test.cc
@@ -13267,11 +13267,13 @@
   TestConnectionCloseQuicErrorCode(QUIC_AEAD_LIMIT_REACHED);
 }
 
+// TODO(b/389762349): Re-enable these tests when sending AckFrequency is
+// restored.
+#if 0
 TEST_P(QuicConnectionTest, SendAckFrequencyFrame) {
   if (!version().HasIetfQuicFrames()) {
     return;
   }
-  SetQuicReloadableFlag(quic_can_send_ack_frequency, true);
   set_perspective(Perspective::IS_SERVER);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _, _, _))
       .Times(AnyNumber());
@@ -13314,7 +13316,6 @@
   if (!version().HasIetfQuicFrames()) {
     return;
   }
-  SetQuicReloadableFlag(quic_can_send_ack_frequency, true);
   set_perspective(Perspective::IS_SERVER);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _, _, _))
       .Times(AnyNumber());
@@ -13346,6 +13347,7 @@
   EXPECT_EQ(captured_frame.requested_max_ack_delay,
             QuicTime::Delta::FromMilliseconds(GetDefaultDelayedAckTimeMs()));
 }
+#endif
 
 TEST_P(QuicConnectionTest, FastRecoveryOfLostServerHello) {
   if (!connection_.SupportsMultiplePacketNumberSpaces()) {
@@ -14322,12 +14324,14 @@
   EXPECT_FALSE(connection_.connected());
 }
 
-// Regresstion test for b/175685916
+// TODO(b/389762349): Re-enable these tests when sending AckFrequency is
+// restored.
+#if 0
+// Regression test for b/175685916
 TEST_P(QuicConnectionTest, TryToFlushAckWithAckQueued) {
   if (!version().HasIetfQuicFrames()) {
     return;
   }
-  SetQuicReloadableFlag(quic_can_send_ack_frequency, true);
   set_perspective(Perspective::IS_SERVER);
 
   QuicConfig config;
@@ -14349,6 +14353,7 @@
                        &SimpleSessionNotifier::WriteOrBufferAckFrequency));
   QuicConnectionPeer::SendPing(&connection_);
 }
+#endif
 
 TEST_P(QuicConnectionTest, PathChallengeBeforePeerIpAddressChangeAtServer) {
   set_perspective(Perspective::IS_SERVER);
diff --git a/quiche/quic/core/quic_sent_packet_manager.cc b/quiche/quic/core/quic_sent_packet_manager.cc
index 2c60d23..62e879c 100644
--- a/quiche/quic/core/quic_sent_packet_manager.cc
+++ b/quiche/quic/core/quic_sent_packet_manager.cc
@@ -131,16 +131,10 @@
     peer_max_ack_delay_ =
         QuicTime::Delta::FromMilliseconds(config.ReceivedMaxAckDelayMs());
   }
-  if (GetQuicReloadableFlag(quic_can_send_ack_frequency) &&
-      perspective == Perspective::IS_SERVER) {
-    if (config.HasReceivedMinAckDelayDraft10Ms()) {
-      peer_min_ack_delay_ = QuicTime::Delta::FromMilliseconds(
-          config.ReceivedMinAckDelayDraft10Ms());
-    }
-    if (config.HasClientSentConnectionOption(kAFF1, perspective)) {
-      use_smoothed_rtt_in_ack_delay_ = true;
-    }
-  }
+  // TODO(b/389762349): set peer_min_ack_delay_ if
+  // config.HasReceivedMinAckDelayDraft10Ms(). Set
+  // use_smoothed_rtt_in_ack_delay_ based on
+  // config.HasClientSentConnectionOption(kAFF1, perspective).
   if (config.HasClientSentConnectionOption(kMAD0, perspective)) {
     ignore_ack_delay_ = true;
   }
@@ -675,7 +669,6 @@
     return frame;
   }
 
-  QUIC_RELOADABLE_FLAG_COUNT_N(quic_can_send_ack_frequency, 1, 3);
   frame.ack_eliciting_threshold = kMaxRetransmittablePacketsBeforeAck;
   auto rtt = use_smoothed_rtt_in_ack_delay_ ? rtt_stats_.SmoothedOrInitialRtt()
                                             : rtt_stats_.MinOrInitialRtt();
diff --git a/quiche/quic/core/quic_sent_packet_manager_test.cc b/quiche/quic/core/quic_sent_packet_manager_test.cc
index d7c051b..925c41b 100644
--- a/quiche/quic/core/quic_sent_packet_manager_test.cc
+++ b/quiche/quic/core/quic_sent_packet_manager_test.cc
@@ -3120,6 +3120,9 @@
   EXPECT_EQ(message_frame->message_length, 0);
 }
 
+// TODO(b/389762349): Re-enable these tests when sending AckFrequency is
+// restored.
+#if 0
 TEST_F(QuicSentPacketManagerTest, BuildAckFrequencyFrame) {
   SetQuicReloadableFlag(quic_can_send_ack_frequency, true);
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
@@ -3146,6 +3149,7 @@
                      QuicTime::Delta::FromMilliseconds(1u)));
   EXPECT_EQ(frame.ack_eliciting_threshold, 10u);
 }
+#endif
 
 TEST_F(QuicSentPacketManagerTest, SmoothedRttIgnoreAckDelay) {
   QuicConfig config;
@@ -3259,6 +3263,9 @@
   EXPECT_EQ(kTestRTT, manager_.GetRttStats()->latest_rtt());
 }
 
+// TODO(b/389762349): Re-enable these tests when sending AckFrequency is
+// restored.
+#if 0
 TEST_F(QuicSentPacketManagerTest, BuildAckFrequencyFrameWithSRTT) {
   SetQuicReloadableFlag(quic_can_send_ack_frequency, true);
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
@@ -3287,6 +3294,7 @@
             std::max(rtt_stats->SmoothedOrInitialRtt() * 0.25,
                      QuicTime::Delta::FromMilliseconds(1u)));
 }
+#endif
 
 TEST_F(QuicSentPacketManagerTest, SetInitialRtt) {
   // Upper bounds.