I hope you are well today and thank you for your question.
If i open a random site ill get a 404 Error.
https://www.yoursite.org/randomstring1234 (Site diddn’t exist)
Is that a page or post? Does it exist?
Please try resaving your site permalink settings.
But if i open this page i will get a Blog overview:
https://www.yoursite.org/netcup-gutschein/randomstring1234/ (site diddnt exist)
The page displays for me as shown in the attached screenshot.