different times for last boot between last and uptime -s

[Ralf Mardorf]

Btw. here are several (irrelevant but also) relevant examples that
explain why the attitude of claiming that one date format is superior to
another is absolutely idiotic: 

https://en.wikipedia.org/wiki/Time_formatting_and_storage_bugs

Fun fact:

"The uncrewed Deep Impact space probe lost communication with Earth on
11 August 2013 because of a time tagging problem; the date was stored as
an unsigned 32-bit integer counting the number of tenth-seconds since
January 1, 2000."

Serious fact:

"The year 10,000 will be the first Gregorian year with five digits.
Although many people at first consider this year to be so far distant
that a problem of this type will never actually occur, certain classes
of calculations in disciplines such as astronomy and physics already
need to work with years of this magnitude and greater."