It should not be a complete surprise that flipped coins do not exactly meet the ideal of fair 50/50 outcomes. After all the stamp on each side must shift the balance, however slightly. Here researchers find the "up" side when flipped is slightly more likely to be the end result.
I suspect dice have a similar bias, especially when you don't give them an energetic shake and throw.
Flipped coins found not to be as fair as thought
https://phys.org/news/2023-10-flipped-coins-fair-thought.html
