Timezones & candle closing question

Is there a ‘standard’ that most people adhere to when it comes to when their 4 hour candles close?

The reason I ask is that I have accounts with 2 brokers and their 4 hour candles close one hour apart from each other. One 4 hour candle closes/opens at 12:00 PM GMT and the other at 1:00 PM GMT.

Is there a more ‘popular’ time convention that ‘most’ traders (particularly the institutional ones) use?