I asked chatGPT and get 2 answers depending on how I asked.…

That’s because both answers are correct

A “day” we know to be 24 hours because that’s how we chose measure it.

A “day”, noon-to-noon is actually less than 24 hours.

to make more sense of why that is or why it’s possible. Assume a day is actually a 360° rotation. In a days worth of time, the earth has rotated 1/365th around the sun. 1/365th of rotation around the sun adds about 1° to the total 360° daily rotation because not only has it spun, it’s in a new location