This occurs when the original payment post date is different from the adjustment post date.  When making an adjustment, if the adjustment post date is different users will receive the prompt:

The adjustment post date you have entered is not the same as the deposit post date. In order to keep this payment in the original deposit, the post dates must be the same. Would you like to proceed with the new adjustment post date and unlink the adjusted payment from this deposit?

If users click "Yes," the revenue will be unlinked from the original deposit.  If they click "No," they'll be unable to save the adjustment.