Deployed React 18: Intermediate Topics game-hub tutorial, Unexpected Application Error! 404 Not Found

Hi everyone!

After completing the React 18: Intermediate Topics Game Hub tutorial, I tried to build the project and deploy it on my own website in a subfolder (Game Hub Tutorial). The homepage loads correctly and all the filters & search are working correctly, also the links in the GameCards are now working correctly (but i had to change them manually in the code - base path isn’t working properly).
But whenever I type an url (incl. slug) to get to the DetailPage or just reload it when it’s already loaded, I get an ‘404 Not Found The requested URL was not found on this server.’ although the page was visited an loaded properly just a second ago!

Has anyone had the same error and can tell me where the problem is?
(I already changed the base url in the vite.config.ts and the routes.ts to match my subfolder) In development & preview it’s working properly

Thanks in advance