The item definition is missing the square brackets around the variable statement
but then in your sitemap you actually define a separate label without the level state variable. If you don’t want to show the level at all there is no need to define it in the item either, no formatting warning should be shown then. Or keep the level formatting (with the correct brackets) in the item definition, then there is no separate label required in the sitemap.
Also just realised that you have Homematic IP, not sure if the level is an integer there or possibly a string, so either [%d %%] or [%s %%].