Calendar on Sharepoint Modern shows dates format, not actual date

Hello Community,

I added a company calendar on the startpage of our sharepoint. Events are shown correctly and everything seems workin fine, but the year, the first day of every month and the current date are always shown as the format it should be in rather than the actual number. As in, the first day of may is shown as "a Mai" (german), the year is shown as "JJJJ" (again, german for "Jahr" I suspect) and the current date is also shwon as "a Apr.". I attached a picture to show you the errors. Can anybody please advise on how to fix that? I tested it on different browsers, different pcs and different accounts, all to the same result.

Best regards

Peter Herold