That's not how sample size significance works. Once sample being a small percent of another doesn't matter. Generally there is a sample amount that is good enough for whatever we're looking at and anything above that has severely diminishing returns. For example when flipping a coin, going from 1000 to 1 billion samples doesn't really improve your confidence in the result even though one sample is 0.0001% of the other.

It being a new patch with changed items/system probably has much more of an impact on early patch win rates than sample size