I am surprised that NTP project is not funded, fully or partially, by larger organizations or governments, given the criticality of the project.
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Notably NTPd doesn't support leap-smear, which means those who absolutely must have monotonic time can't use it at all.
... shouldn’t be using a Unix timestamp, or anything else that’s not a count of SI seconds elapsed since a fixed reference point, to begin with.
[1] https://people.csail.mit.edu/rachit/post/you-have-built-a-co..., https://news.ycombinator.com/item?id=29891428