UTC-12 and UTC+12 both exist. So while it is 1 second past new year's for UTC+12, there is still 24 hours until UTC-12 has it's new year. Browsers also don't always report time zones correctly (such as Firefox with privacy settings).

So, for many events that are date-specific, many websites (such as Google doodles and Reddit's special events) often opt to just make these events multi-day.

Catt0s said:
UTC-12 and UTC+12 both exist. So while it is 1 second past new year's for UTC+12, there is still 24 hours until UTC-12 has it's new year. Browsers also don't always report time zones correctly (such as Firefox with privacy settings).

So, for many events that are date-specific, many websites (such as Google doodles and Reddit's special events) often opt to just make these events multi-day.

I feel like if it's something that would be spoiled if it wasn't a simultaneous rollout it'd be best to at 00:00 GMT so that it's at least the day for ~half of the world. the update was put out around 16:00 GMT the only people it was April 1st for were likely asleep, because that was barely 5 AM in New Zealand.