Have you noticed the similar language used in Matthew 24:21-22 and Daniel 12:1?
NWT – For then there will be great tribulation+ such as has not occurred since the world’s beginning until now, no, nor will occur again.+ 22 In fact, unless those days were cut short, no flesh would be saved; but on account of the chosen ones those days will be cut short.+
Daniel 12:1b And there will occur a time of distress such as has not occurred since there came to be a nation until that time. And during that time your people will escape, everyone who is found written down in the book. 2 And many of those asleep in the dust of the earth will wake up, some to everlasting life and others to reproach and to everlasting contempt.