Changed the homepage setting to a different page, but the old page still appears

Hi!

I made a new homepage for https://www.augenblickmal.eu and changed the setting in Settings – Reading, but the old homepage still shows up when opening the website (I made the change hours ago).

– I tested it in four different browsers including mobile outside my wifi. All show the same – wrong/old – homepage.
– I wasn’t using a caching plugin, but I installed one now just to see if it would help to delete the cache – no change.
– I asked someone who has never visited this website before to open it, and they also got the old homepage.
– I tried to set the old homepage to status “draft” – then I got the 404/search page instead of the page which is actually defined as the homepage in the settings (https://www.augenblickmal.eu/mehr-gesundheit-und-achtsamkeit-in-der-digitalen-welt/).
– No matter which other page I set as the homepage – as long as the old homepage (https://www.augenblickmal.eu/digitalwellness) exists and is published, that’s the one that shows up.

I have never experienced anything like this before. Any idea what I should do?

Thanks!