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Finder can now show milli seconds in timestamps. Is this a recent change in macOS?

as List Get Info - File as Columns

You can test it yourself, here how to show milliseconds for Finder. I have chosen 5 digits. This is the maximum.

System Preferences -> Language & Region -> Advanced... -> Times -> Short:

Show milliseconds

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This change happened with the introduction of the APFS file system.

Traditionally on Mac OS X the computer's disk drives were formatted with the HFS+ file system. This file system stores time stamps with a 1 second granularity. If you save a file at 12:04:31.4938, the file system actually only records 12:04:31 and doesn't have any more information for Finder to display.

macOS High Sierra was the first version of the operating system to replace HFS+ with APFS as the default file system. The APFS file system stores time stamps with a nano-second granularity. This means that if you save a file at 12:04:31.4938, the file system actually stores that full time stamp - allowing Finder to actually display that exact time stamp.

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    Of course, there's a difference between precision and accuracy. NTP "can usually maintain time to within tens of milliseconds over the public Internet, and can achieve better than one millisecond accuracy in local area networks under ideal conditions."
    – Barmar
    Sep 17 at 14:40
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    @barmar I think no one at all were confused and thought that the ability to store precision time stamps in the file system would suddenly mean that the computer’s clock would align completely with global time. When you talk about time stamps on a local file system, they are relative to the computer’s own clock - and not necessarily corresponding to what the actual time of day is as read out on a wrist watch or on a precision clock.
    – jksoegaard
    Sep 17 at 16:58

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