No. THis is not made-up shit. This is observed. The explanation for why we observe it is different, depending on your framework.
The Earth’s rotation from Sun overhead to Sun overhead is a day. On a globe Earth, the Earth is also revolving around the sun, so we have to turn a little bit more than 360 degrees for the sun to be overhead again. But the stars are farther away, and their apparent movement across the sky doesn’t match the sun’s. So we see a sidereal difference between the two references, sun overhead and star overhead.
On a flat Earth, the sun, moon, stars, and each individual planet cross the sky independently, to no standard that can describe all of their orbits in any rational sense. But you still see that the time it takes a star to go from a point in the sky to the same point is different from the sun making the same movement.
But i’m surprised you don’t have Leap Year and Leap Second up there on the list…