There's some center-of-gravity and shifting of things as you burn up fuel. Not an expert, so here's where the streamer talks a bit about it, including why the s

There's some center-of-gravity and shifting of things as you burn up fuel. Not an expert, so here's where the streamer talks a bit about it, including why the space shuttle did it too: https://youtu.be/NJR4gZBLMNw?t=1195 https://youtu.be/NJR4gZBLMNw?t=1195