эммм я не умею создавать песочницу)))
const start = moment()
.tz('America/Los_Angeles')
// .format('YYYY-MM-DD HH:mm:ss');
const end = moment(will_active_at?.replace(".000Z", ""))
// .format('YYYY-MM-DD HH:mm:ss');
let diff = moment(end).diff(moment(start));
console.log('You waited: START: ', moment.utc(start.format('YYYY-MM-DD HH:mm:ss')).toISOString());
console.log('You waited: END: ', moment.utc(end.format('YYYY-MM-DD HH:mm:ss')).toISOString());
console.log('You waited: DIFF: ', start.diff(end, 'minutes'));