Looks like the "A Native Collection hasn't been disposed" error at this point is only present due to use not disposing of the NetworkDriver when we're done with Relay.

Assets/Scripts/Relay/RelayUtpClient.cs

             m_localUser.onChanged -= OnLocalChange;
             Leave();
             Locator.Get.UpdateSlow.Unsubscribe(UpdateSlow);
+            m_networkDriver.Dispose();
         }
         public void OnDestroy()
         {

Assets/Scripts/Relay/RelayUtpSetup.cs

             }
         }
         #endregion
+
+        private void OnDestroy()
+        {
+            if (!m_isRelayConnected && m_networkDriver.IsCreated)
+                m_networkDriver.Dispose();
+        }
     }
 
     /// <summary>
             }
             else
             {
-                RelayUtpClient watcher = gameObject.AddComponent<RelayUtpClient>();
-                watcher.Initialize(m_networkDriver, m_connections, m_localUser, m_localLobby);
-                m_onJoinComplete(true, watcher);
+                m_isRelayConnected = true;
+                RelayUtpClient client = gameObject.AddComponent<RelayUtpClient>();
+                client.Initialize(m_networkDriver, m_connections, m_localUser, m_localLobby);
+                m_onJoinComplete(true, client);
                 LobbyAsyncRequests.Instance.UpdatePlayerRelayInfoAsync(m_allocation.AllocationId.ToString(), m_localLobby.RelayCode, null);
             }
         }

Assets/Scripts/Tests/PlayMode/LobbyRoundtripTests.cs

 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
+using System.Text.RegularExpressions;
 using Unity.Services.Lobbies;
 using Unity.Services.Lobbies.Models;
 using UnityEngine;
         public void Teardown()
         {
             m_auth?.Dispose();
-            LogAssert.ignoreFailingMessages = false;
         }
 
         /// <summary>
         public IEnumerator DoRoundtrip()
         {
             #region Setup
-            LogAssert.ignoreFailingMessages = true; // Not sure why, but when auth logs in, it sometimes generates an error: "A Native Collection has not been disposed[...]." We don't want this to cause test failures, since in practice it *seems* to not negatively impact behavior.
-
             // Wait a reasonable amount of time for sign-in to complete.
             if (!m_didSigninComplete)
                 yield return new WaitForSeconds(3);
 
             // Some error messages might be asynchronous, so to reduce spillover into other tests, just wait here for a bit before proceeding.
             yield return new WaitForSeconds(3);
-            LogAssert.ignoreFailingMessages = false;
         }
 
         /// <summary>
         public IEnumerator OnCompletesOnFailure()
         {
-            LogAssert.ignoreFailingMessages = true;
+            LogAssert.Expect(LogType.Exception, new Regex(".*400 Bad Request.*"));
             if (!m_didSigninComplete)
                 yield return new WaitForSeconds(3);
             if (!m_didSigninComplete)

Assets/Scripts/Tests/PlayMode/RelayRoundTripTests.cs

         public void Teardown()
         {
             m_auth?.Dispose();
-            LogAssert.ignoreFailingMessages = false;
         }
 
         /// <summary>
         [UnityTest]
         public IEnumerator DoBaseRoundTrip()
         {
-            LogAssert.ignoreFailingMessages = true;
             if (!m_didSigninComplete)
                 yield return new WaitForSeconds(3);
             if (!m_didSigninComplete)