fix

com.unity.uiwidgets/Runtime/engine/UIWidgetsPanel.cs

             TryEnableOnDemandGC();
 #endif
             Application.lowMemory += () => {
-                GarbageCollector.GCMode = GarbageCollector.Mode.Enabled;
+#if !UNITY_EDITOR
+                TryDisableOnDemandGC();
+#endif
-                GarbageCollector.GCMode = GarbageCollector.Mode.Disabled;
+#if !UNITY_EDITOR
+                TryEnableOnDemandGC();
+#endif
             };