I tried a few approaches with this, but i do know that dealing with the Schema on any occasion is a bit finicky for want of a better word, Ive updated it to reflect the dob is a date but still hit this error
const schema = new Parse.Schema('Profile')
schema.addField('dob', 'Date', { required: false});
schema.addDate('dob', { required: false});
await schema.update();