We tried to submit a new build to iTunesConnect for updating an existing application. It is a quick patch for fixing one server url.
We changed two files: REST.plis
This is explained right here:
The bundle uses a bundle name or display name associated with an Apple app.
This is likely a new automated check, and that's why your previous versions went through with no problems before.
It's saying that your app is using a display name (the name below the icon on the homescreen) that an app made by Apple uses - for example, if the label said "Mail", then you could expect it to be rejected for this reason.
Change your app name to something Apple doesn't use in their apps.