The Fourth Circuit has determined that an immigration judge may render a mixed credibility determination —deeming an applicant’s testimony credible as to one subject but not another. “In the case of a mixed credibility finding, a presumption of credibility should be applied by the Board on appeal concerning the portion of testimony not explicitly determined incredible.”
The full text of Ayala-Osegueda v. Garland can be found here: https://www.ca4.uscourts.gov/opinions/221707.P.pdf