I don't know the first thing about football, only that it has the words "foot" and "ball", none of which apply to the American variant who is played with hands and a (geometric) lemon[1] :p

I figured FIFA/UEFA who both standardised on 105m, sensibly factored ±5m to account for Heisenberg uncertainty when approaching relativistic speeds. This is very well depicted - complete with curvature of space, train paradox, spooky action at a distance, time dilation, and other relativistic oddities - in a documentary I watched when I was young; if only I could recall the original name...

EDIT: I think it was キャプテン翼.[2]

[1]: https://en.wikipedia.org/wiki/Lemon_(geometry)

[2]: https://www.youtube.com/watch?v=ke5AZhJCPSg