as the fixed default instead because that's simply the default today. there is no reason to do something else, except if you want to produce threads like this.
it's a time change in 1927 in shanghai as others mentioned.
basically, that 23:54:07 in shanghai, the local standard time, after then a little while it turned to the next day at 00:00:00. but then it switched back to 23:54:08 for the local standard time. so, that's why the difference is 343 seconds not 1 second.
this also can mess up with other places like the us. in us they have daylight saving time. when the daylight saving time starts the time goes forward by 