The speed of light is an upper limit on how fast matter, energy, and information can move through space. The expansion of space during the Big Bang (and afterwards at a much slower rate) is something fundamentally different from motion. It’s a “metric expansion,” which doesn’t require anything to move within space and is not limited by the speed of light. It’s not even measured in the same units as speed; speed is distance/time, whereas expansion is (distance/time)/distance, which oddly collapses down to just units of 1/time.