EPUB OCF says U+E007F is disallowed as one of the two deprecated characters in the Tags and Variation Selectors Supplement.

But E+E007F CANCEL TAG was reinstated as non-deprecated in Unicode 9.0, see the change history for the Unicode Character Database

The stateful tag terminator U+E007F CANCEL TAG, formerly deprecated, was reinstated to non-deprecated, for use in emoji contexts.

See also the up-to-date list of deprecated characters in the latest UCD PropList.txt file (search for "Deprecated").