After migrating from EE3 to EE4, it no longer displays many pages: Not found Error 404. For critical pages everything is OK and even after re-saving the permalinks it does not work.
It is about the following page: https://www.verein-ifz.ch/events/virtueller-winterevent-2023-mit-john-bercow/
Also on the other pages Transaction and Thank you comes only not found – Error 404.