The Second Circuit has determined that death threats are no per se past persecution, noting that they will rise to the level of persecution only if the applicant can point to aggravating circumstances indicating that the death threat was “so imminent or concrete” or “so menacing as itself to cause actual suffering or harm.”
The full text of KC v. Garland can be found here: https://ww3.ca2.uscourts.gov/decisions/isysquery/ffede890-ad84-46c5-93e1-549ef45053a5/9/doc/20-3043_opn.pdf