I was playing a survival world I generated in 1.18 pre-release 5 and was exploring a cave. I  later found an amethyst geode and noticed an oddity with it (shown in the screenshot.) I also copied the world seed and re-generated it in 1.18 pre-release 6 and the geode had not changed. It seemed to have an odd top section that did not look normal. The seed is 8029098402006770505 for this particular geode. I'm not sure if others have generated like this but I know it affects the previous pre-release as well.

Edit: From the other side it looks like it extended the circular shape to the side of the geode which makes the entire geode less circular.