Any idea why timestamps would be showing such odd difference in value to the UTC Time?

const timestampMs = Date.parse(msg.payload.time) / 1000;
  "timestamp_ms": Math.floor(timestampMs)

when running the same logic elsewhere my timestamp in Unix matches to the time in ISO 8601 but in tag browser has a mismatch. not sure if this is the cause but malaysia is actually GMT +8 hours https://cdn.discordapp.com/attachments/984083100520808478/1316796357008429096/image.png?ex=675c59ac&is=675b082c&hm=1217b119242a8b74042d3f30dec3991824274f9b2ee587e3cbbab65a926efbe7&