On some brokers (Oanda for example) the timezone switches twice for DST if the selected timezone uses EU DST (as shown in the selection of London UTC which is different from the standard UTC in that it follows EU DST).
Because the US DST switches first, the daily open (and thus, 4h candle opens) is different and starts an hour later (leading to odd-numbered times in this case).
Once EU DST takes effect, the day opens at the usual time again.