add

app/admin/library/crud/stubs/mixins/model/setters/arrayToString.stub

@@ -0,0 +1,5 @@
+
+    public function set{%field%}Attr($value): string
+    {
+        return is_array($value) ? implode(',', $value) : $value;
+    }

app/admin/library/crud/stubs/mixins/model/setters/time.stub

@@ -0,0 +1,5 @@
+
+    public function set{%field%}Attr($value): ?string
+    {
+        return $value ? date('H:i:s', strtotime($value)) : $value;
+    }