diff --git a/media/engine/webrtc_video_engine.cc b/media/engine/webrtc_video_engine.cc
index b3afbf9fd8..dd91eb2782 100644
--- a/media/engine/webrtc_video_engine.cc
+++ b/media/engine/webrtc_video_engine.cc
@@ -2502,9 +2502,9 @@ WebRtcVideoChannel::WebRtcVideoSendStream::CreateVideoEncoderConfig(
   // `legacy_scalability_mode` and codec used.
   encoder_config.number_of_streams = parameters_.config.rtp.ssrcs.size();
   bool legacy_scalability_mode = true;
-  // TODO(https://crbug.com/webrtc/14884): When simulcast VP9 is ready to ship,
-  // don't require a field trial to set `legacy_scalability_mode` to false here.
-  if (call_->trials().IsEnabled("WebRTC-AllowDisablingLegacyScalability")) {
+  // TODO(https://crbug.com/webrtc/14884): This is only used as a kill-switch
+  // in case of serious bugs - when this reaches Stable, delete the field trial.
+  if (!call_->trials().IsDisabled("WebRTC-AllowDisablingLegacyScalability")) {
     for (const webrtc::RtpEncodingParameters& encoding :
          rtp_parameters_.encodings) {
       if (encoding.scalability_mode.has_value()) {
diff --git a/media/engine/webrtc_video_engine_unittest.cc b/media/engine/webrtc_video_engine_unittest.cc
index c86ceb6176..e47f365491 100644
--- a/media/engine/webrtc_video_engine_unittest.cc
+++ b/media/engine/webrtc_video_engine_unittest.cc
@@ -8463,7 +8463,9 @@ TEST_F(WebRtcVideoChannelTest,
       webrtc::ScalabilityModeFromString(kDefaultScalabilityModeStr);
   EXPECT_EQ(2, stream->num_encoder_reconfigurations());
   webrtc::VideoEncoderConfig encoder_config = stream->GetEncoderConfig().Copy();
-  EXPECT_EQ(1u, encoder_config.number_of_streams);
+  // When `scalability_mode` has been specified on any encoding, we do not
+  // reduce the number of simulcast streams.
+  EXPECT_EQ(3u, encoder_config.number_of_streams);
   EXPECT_THAT(encoder_config.simulcast_layers,
               ElementsAre(Field(&webrtc::VideoStream::scalability_mode,
                                 ScalabilityMode::kL3T3),
@@ -8476,7 +8478,11 @@ TEST_F(WebRtcVideoChannelTest,
   // VideoStreams are created appropriately for the simulcast case.
   EXPECT_THAT(stream->GetVideoStreams(),
               ElementsAre(Field(&webrtc::VideoStream::scalability_mode,
-                                ScalabilityMode::kL3T3)));
+                                ScalabilityMode::kL3T3),
+                          Field(&webrtc::VideoStream::scalability_mode,
+                                kDefaultScalabilityMode),
+                          Field(&webrtc::VideoStream::scalability_mode,
+                                kDefaultScalabilityMode)));
 
   // GetParameters.
   parameters = send_channel_->GetRtpSendParameters(last_ssrc_);
diff --git a/pc/peer_connection_simulcast_unittest.cc b/pc/peer_connection_simulcast_unittest.cc
index 1f5f17a517..c0513b2a6a 100644
--- a/pc/peer_connection_simulcast_unittest.cc
+++ b/pc/peer_connection_simulcast_unittest.cc
@@ -60,7 +60,6 @@
 #include "rtc_base/thread.h"
 #include "rtc_base/unique_id_generator.h"
 #include "system_wrappers/include/metrics.h"
-#include "test/field_trial.h"
 #include "test/gmock.h"
 #include "test/gtest.h"
 
@@ -1432,13 +1431,8 @@ TEST_F(PeerConnectionSimulcastWithMediaFlowTests,
               Optional(std::string("L3T3_KEY")));
 }
 
-// TODO(https://crbug.com/webrtc/14884): A field trial shouldn't be needed to
-// get spec-compliant behavior!
 TEST_F(PeerConnectionSimulcastWithMediaFlowTests,
        SendingThreeEncodings_VP9_Simulcast) {
-  test::ScopedFieldTrials field_trials(
-      "WebRTC-AllowDisablingLegacyScalability/Enabled/");
-
   rtc::scoped_refptr<PeerConnectionTestWrapper> local_pc_wrapper = CreatePc();
   rtc::scoped_refptr<PeerConnectionTestWrapper> remote_pc_wrapper = CreatePc();
   ExchangeIceCandidates(local_pc_wrapper, remote_pc_wrapper);
@@ -1503,17 +1497,9 @@ TEST_F(PeerConnectionSimulcastWithMediaFlowTests,
   EXPECT_THAT(*outbound_rtps[2]->scalability_mode, StrEq("L1T3"));
 }
 
-// TODO(https://crbug.com/webrtc/15005): A field trial shouldn't be needed to
-// get spec-compliant behavior! The same field trial is also used for VP9
-// simulcast (https://crbug.com/webrtc/14884).
 TEST_F(PeerConnectionSimulcastWithMediaFlowTests,
        SendingThreeEncodings_AV1_Simulcast) {
-  test::ScopedFieldTrials field_trials(
-      "WebRTC-AllowDisablingLegacyScalability/Enabled/");
-
   rtc::scoped_refptr<PeerConnectionTestWrapper> local_pc_wrapper = CreatePc();
-  // TODO(https://crbug.com/webrtc/15011): Expand testing support for AV1 or
-  // allow compile time checks so that gates like this isn't needed at runtime.
   if (!HasSenderVideoCodecCapability(local_pc_wrapper, "AV1")) {
     RTC_LOG(LS_WARNING) << "\n***\nAV1 is not available, skipping test.\n***";
     return;