diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 88eed21..bb84ef7 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -1000,22 +1000,6 @@
   sent_packet_manager_.MarkInitialPacketsForRetransmission();
 }
 
-bool QuicConnection::HasIncomingConnectionId(
-    QuicConnectionId connection_id) const {
-  if (quic_deprecate_incoming_connection_ids_) {
-    QUIC_RELOADABLE_FLAG_COUNT(quic_deprecate_incoming_connection_ids);
-    // TODO(haoyuewang) Inline this after the flag is deprecated.
-    return connection_id == original_destination_connection_id_;
-  }
-  for (QuicConnectionId const& incoming_connection_id :
-       incoming_connection_ids_) {
-    if (incoming_connection_id == connection_id) {
-      return true;
-    }
-  }
-  return false;
-}
-
 void QuicConnection::SetOriginalDestinationConnectionId(
     const QuicConnectionId& original_destination_connection_id) {
   QUIC_DLOG(INFO) << "Setting original_destination_connection_id to "
@@ -1024,11 +1008,6 @@
                   << default_path_.server_connection_id;
   QUICHE_DCHECK_NE(original_destination_connection_id,
                    default_path_.server_connection_id);
-  if (!quic_deprecate_incoming_connection_ids_) {
-    if (!HasIncomingConnectionId(original_destination_connection_id)) {
-      incoming_connection_ids_.push_back(original_destination_connection_id);
-    }
-  }
   InstallInitialCrypters(original_destination_connection_id);
   QUICHE_DCHECK(!original_destination_connection_id_.has_value())
       << original_destination_connection_id_.value();
@@ -1055,7 +1034,7 @@
       GetServerConnectionIdAsRecipient(header, perspective_);
 
   if (server_connection_id == default_path_.server_connection_id ||
-      HasIncomingConnectionId(server_connection_id)) {
+      server_connection_id == original_destination_connection_id_) {
     return true;
   }
 
diff --git a/quic/core/quic_connection.h b/quic/core/quic_connection.h
index 7b0a2f5..19faa19 100644
--- a/quic/core/quic_connection.h
+++ b/quic/core/quic_connection.h
@@ -1707,9 +1707,6 @@
   // Returns the largest sent packet number that has been ACKed by peer.
   QuicPacketNumber GetLargestAckedPacket() const;
 
-  // Whether incoming_connection_ids_ contains connection_id.
-  bool HasIncomingConnectionId(QuicConnectionId connection_id) const;
-
   // Whether connection is limited by amplification factor.
   bool LimitedByAmplificationFactor() const;
 
@@ -2157,11 +2154,6 @@
   quiche::QuicheCircularDeque<PendingPathChallenge>
       pending_path_challenge_payloads_;
 
-  // Set of connection IDs that should be accepted as destination on
-  // received packets. This is conceptually a set but is implemented as a
-  // vector to improve performance since it is expected to be very small.
-  std::vector<QuicConnectionId> incoming_connection_ids_;
-
   // When we receive a RETRY packet or some INITIAL packets, we replace
   // |server_connection_id_| with the value from that packet and save off the
   // original value of |server_connection_id_| into
@@ -2288,9 +2280,6 @@
       GetQuicReloadableFlag(
           quic_group_path_response_and_challenge_sending_closer);
 
-  const bool quic_deprecate_incoming_connection_ids_ =
-      GetQuicReloadableFlag(quic_deprecate_incoming_connection_ids);
-
   const bool reset_per_packet_state_for_undecryptable_packets_ =
       GetQuicReloadableFlag(
           quic_reset_per_packet_state_for_undecryptable_packets);
diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index 081c822..ff44d6a 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -115,8 +115,6 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_conservative_cwnd_and_pacing_gains, false)
 // If true, validate that peer owns the new address once the server detects peer migration or is probed from that address, and also apply anti-amplification limit while sending to that address.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_server_reverse_validate_new_path3, true)
-// If ture, replace the incoming_connection_ids check with original_destination_connection_id check.
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_deprecate_incoming_connection_ids, true)
 // Queue packets to attempt decryption later until the handshake is complete.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_queue_until_handshake_complete, false)
 // When the STMP connection option is sent by the client, timestamps in the QUIC ACK frame are sent and processed.