Hi Maria,
This is an interesting one, and a good point to ask for sure! I believe that most folks just wouldnt have any CAB meetings during the code freeze periods, and thus the approvals wouldnt occur, and the change orders would just sit and wait until the code freeze is over. I dont believe there is a way out of the box to simply disable CAB functionality. You may be able to use a Data Partition constraint such that they cant set those changes to approved, but I have never played around with doing that - just a thought if you want to give that a shot.
Hope this gives you a bit of help here. You can also always post an idea to the communities with your use case to have a way to disable CAB approvals during code-freeze time frames that can be specified and stored.
Thanks,
Jon I.