Add Room.HasEnded helper method

osu.Game/Graphics/OsuColour.cs

@@ -200,7 +200,7 @@ namespace osu.Game.Graphics
         /// </summary>
         public Color4 ForRoomStatus(Room room)
         {
-            if (DateTimeOffset.Now >= room.EndDate)
+            if (room.HasEnded)
                 return YellowDarker;
 
             switch (room.Status)

osu.Game/Online/Rooms/Room.cs

@@ -374,6 +374,15 @@ namespace osu.Game.Online.Rooms
             RecentParticipants = other.RecentParticipants;
         }
 
+        /// <summary>
+        /// Whether the room is no longer available.
+        /// </summary>
+        /// <remarks>
+        /// This property does not update in real-time and needs to be queried periodically.
+        /// Subscribe to <see cref="EndDate"/> to be notified of any immediate changes.
+        /// </remarks>
+        public bool HasEnded => DateTimeOffset.Now >= EndDate;
+
         [JsonObject(MemberSerialization.OptIn)]
         public class RoomPlaylistItemStats
         {

osu.Game/Screens/OnlinePlay/Lounge/Components/RoomStatusPill.cs

@@ -59,7 +59,7 @@ namespace osu.Game.Screens.OnlinePlay.Lounge.Components
         {
             Pill.Background.FadeColour(colours.ForRoomStatus(room), 100);
 
-            if (DateTimeOffset.Now >= room.EndDate)
+            if (room.HasEnded)
                 TextFlow.Text = RoomStatusPillStrings.Ended;
             else
             {

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerRoomManager.cs

@@ -30,7 +30,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
 
             // this is done here as a pre-check to avoid clicking on already closed rooms in the lounge from triggering a server join.
             // should probably be done at a higher level, but due to the current structure of things this is the easiest place for now.
-            if (DateTimeOffset.Now >= room.EndDate)
+            if (room.HasEnded)
             {
                 onError?.Invoke("Cannot join an ended room.");
                 return;