You need to clarify which elements on the page you expect to be hidden in order for us to help you.
From what I can see, the elements you are attempting to hide do not exist on this page. Therefore, getElementById() would return null, triggering the following error in the developer console:
Uncaught TypeError: document.getElementById(...) is null
You cannot change CSS properties on elements that do not exist. If these elements only exist for specific locales, you should first check for the existence of each element. You could create an array with the ID of each element, loop through it and check for the existence of each one in turn:
// This code has not been tested. Use it at your own risk.
const items = [
'neuigkeiten-container',
'Bundesland-5',
'Bundesland-5-label',
'jobs-link',
'guetesiegel-link',
'neuigkeiten-link',
'neuigkeiten-footerlink',
'jobs-footerlink',
'guetesiegel-footerlink',
'Bundesland-6',
'Bundesland-6-label',
'bio-oil-stellt-vor'
];
items.forEach(function (item) {
const element = document.getElementById(item);
if (element) {
element.style.display = 'none';
}
});