I've had a similar thing happen when I updated to 1.18.0. It told me that I didn't have enough storage to save my world, even though the storage bar is nowhere near full. After closing the game and opening it again, it told me it restored corrupted save files. I loaded into the world again and the textures were broken and I had no character model. This didn't become an issue until I entered the deep dark. My world's size is 953.1MB which is also something that happened after the 1.18.0 world corruption because before that it was 572.1MB. I will attach a short clip of gameplay of the corrupted world.