diff --git a/src/core/singletons/array.ts b/src/core/singletons/array.ts
index 7f31bafc7..77a1be206 100644
--- a/src/core/singletons/array.ts
+++ b/src/core/singletons/array.ts
@@ -37,10 +37,6 @@ export class CoreArray {
      * @return Flattened array.
      */
     static flatten<T>(arr: T[][]): T[] {
-        if ('flat' in arr) {
-            return (arr as any).flat(); // eslint-disable-line @typescript-eslint/no-explicit-any
-        }
-
         return (<T[]> []).concat(...arr);
     }