On candle request date doesn't match

[nomisx]

On a candle request, the response is not giving the same date in return.
In the request is:
bitvavo.websocket.candles('SHIB-EUR', '1d', { start: 1623628800000 }); // Mon Jun 14 2021 00:00:00

response is time is:
1633910400000 // Mon Oct 11 2021 00:00:00

The difference is 4 months.
Am I doing something wrong?

Simon