Fix song select beatmap difficulty count not updating when deleting

osu.Game/Screens/Select/BeatmapCarousel.cs

@@ -49,6 +49,11 @@ namespace osu.Game.Screens.Select
         /// </summary>
         public Action? BeatmapSetsChanged;
 
+        /// <summary>
+        /// Triggered when the deleted <see cref="BeatmapSets"/> change.
+        /// </summary>
+        public Action? DeletedBeatmapSetsChanged;
+
         /// <summary>
         /// Triggered after filter conditions have finished being applied to the model hierarchy.
         /// </summary>
@@ -353,6 +358,8 @@ namespace osu.Game.Screens.Select
 
             if (!Scroll.UserScrolling)
                 ScrollToSelected(true);
+
+            DeletedBeatmapSetsChanged?.Invoke();
         });
 
         public void UpdateBeatmapSet(BeatmapSetInfo beatmapSet) => Schedule(() =>

osu.Game/Screens/Select/SongSelect.cs

@@ -162,6 +162,7 @@ namespace osu.Game.Screens.Select
                 BleedBottom = Footer.HEIGHT,
                 SelectionChanged = updateSelectedBeatmap,
                 BeatmapSetsChanged = carouselBeatmapsLoaded,
+                DeletedBeatmapSetsChanged = updateVisibleBeatmapCount,
                 FilterApplied = updateVisibleBeatmapCount,
                 GetRecommendedBeatmap = s => recommender?.GetRecommendedBeatmap(s),
             }, c => carouselContainer.Child = c);