cache – Non-administrators getting cached messages

I'm having a strange problem with caching wordpress publications. If an administrator is logged in, he does not receive a cached publication, but a regular visit is cached. I do not have cache plugins and the only way to update the message is to restart apache2.

I have cloudflare running, but that's only caching images and js.

I have the impression that it has something to do with Apache since the restart, which forces the pages to update, but I can not figure out what I should look at.

Any suggestion would be appreciated. Thank you!