Unable to process app at this time due to a general error

Is this the App Store's fault?

Very probably.

What should I do?

You may need to just wait until the unspecified general error is fixed. Usually this sort of errors will be fixed in hours, when unlucky a few days.

By the way, you should better use the right tag. XcodeKit is not appropriate for this issue. You can use the tag App Store Connect.