The issue ia likely a bug in App Store Connect.
The internal records remained stuck in a review-ready state even though they are no longer attached to any visible submission. The system still considers them active or “inflight,” preventing them from being added to another draft or replaced.
There are only two possible solutions:
The orphaned review associations need to be cleared or the records reset to an editable, pre-submission state. This will require involvement from the correct group at Apple.
Recreate IAPs and Subscriptions. Keep in mind that you cannot reuse the same IDs so your app will also need to be updated to utilize these new IDs.