Exactly this.

For example the iOS app failed first time as I accidentally used "Free" in the app name, and the app declared support for UIBackgroundModes but they were "unable to locate any features that require persistent audio". The dictation keyboard switched you to the app, then if you left would keep recording... fairly basic and obvious stuff. I could have either gone back and argued the case, or simply rip it out which I opted for.

It's now failed again because: The keyboard extension does not provide any functionality when the "Full Access" setting is toggled off.

Well no, hardly my fault you've locked down the usefulness of third-party keyboards, but now I've added a full keyboard in there so it's a bit more useful without that access. I don't expect any users to ever see this. Admittedly this was more frustrating when that would be a couple days work, not just a quick prompt, to fix.

Good luck with your app. Don't worry too much, you can generally work through their issues... but it can be a slow process. Make sure you leave plenty of time between your submission and when you want to launch!