Flatness Problem

In the universe, according to Einstein’s equation, any deviation from flatness in an expanding universe filled with matter or radiation only gets bigger as the universe expands. So any tiny deviation from flatness at a much earlier time would have grown very large by now. If the deviation from flatness is very small now, there must have been an immeasurable small amount of deviation at the start of the Big Bang. Today, there is a very small amount of deviation from the flat spatial geometry. As there is a bit of spatial curvature, it signifies that there must have been an immeasurably small amount of curvature during the time that the Big Bang occurred. However, according to the Big Bang Theory, there was no deviation of spatial curvature, and thus contradicts the Big Bang Theory.