multisite - Hook into 'admin_url' but only on Mysites admin bar menu

I'd like to alter admin url only inside "My Sites" admin bar menu..

I tried this filter:

add_filter( 'admin_url', function( $url, $path, $blog_id ){ return $url . "str" });

but when I do that it messes up every post edit post link?

Is there a way I can edit admin url only to that scoped section?

Thanks for any insights!