Steeldancer (paraphrased)
According to General Relativity, there should be spatial distortion in speed bubbles. So, why does no one notice it?
Brandon Sanderson (paraphrased)
There is spatial distortion in speed bubbles, that's why bullets are refracted when they enter a bubble. However, I played with it a bit, and ignore the redshift that should happen. The barrier of the bubble absorbs it, otherwise everyone would just be irradiated.