Ingame clock runs a few seconds late, based on game start time

[steep basin]

It seems the game starts counting the time from when the game starts, but without taking the current seconds into account, and then increments the clock every 60 seconds.
In the screenshot the game started around 21:15:50 (21:00 = 9pm), and the ingame clock stayed on 9:15 until 21:16:50
Tried this is few other times, and this is consistent, ie when i start the game early in the minute (e.g. at :20), the clock will only be a 20 seconds late.

[tawdry bane]

The clock on the floor is not updated in real time.

You'll notice there are certain actions which will cause the clock to update.

But for performance reasons, it is not updated constantly.

The behaviour you are seeing may be related in part to the update interval not being 1:1 with the clock.