Exit polls don’t generally report the number of refusals. Whether or not this introduces bias depends, obviously, on whether the people who refuse tend to vote for the candidates in the same proportion as the people who answer.
In past years, it appears that they did, because we never saw a consistent pattern of error. (An individual exit poll could always be wrong, since all polls have a margin of error, but it was equally likely to err in favor of Republicans or Democrats.)
In this election, a larger percentage of Republicans apparently refused to answer. The logical reason would be ever-growing Republican mistrust of the media.
The unpredictability of this variation in refusal rates will probably make exit polls useless as a forecasting tool, so we’ll go back to waiting for the actual votes. Bravo, I say!
FWIW, I categorically refuse to say how I voted. mrAru doesn’t even know who I vote for. If I am not even telling my husband, best friend in the whole world and lover who I voted for, why should I tell anybody else. Secret ballots are a right, and a protection.