[dodobirdlord]

All observers observer all clocks to advance monotonically forward in time, regardless of their location or relative speed, unless the clock is moving at the speed of light. But the rate that each clock is observed to advance at depends on things like relative speed, acceleration, and the curvature of spacetime.

[JdeBP]

... unless it's the system clock in Linux, with the hardware RTC set to be interpreted as local time, and one is watching a system boot on a machine that is set up as east of the Prime Meridian (i.e. the hardware RTC is ahead of UTC). (-:

* https://unix.stackexchange.com/a/600490/5132

[dodobirdlord]

Given that Unix time specifically doesn’t handle leap seconds, a system clock is not a clock by the conventional definition.