The answer to the question is simple...
If Kamala for WHATEVER reason decides to not certify, the electors must return to the state until that (those) state legislatures convene to confirm (certify) them as legitimately elected OR appoint new ones.
She has no absolutely no power to make such a decision, and there is no mechanism for the Electors to go back to the states once the certification deadlines have passed and the Electors have cast their votes.
If Electors are disqualified, that would have to be done by vote of Congress to prevent them from being counted. If once the count of accepted Electors does not equal a majority for either candidate, the House elects the President and the Senate elects the Vice President.