Large area of grass foliage does not receive dynamic shadow

As shown in the image here, when playing the game, there is always a clear line dividing my grass foliages into two parts. On the left side, all grass tend to case dynamic shadows normally, and on the right side, no shadow is cast. After moving the spawn location of the main character several times, I realized that it seems only the blocks near the spawn location of the player render the dynamic shadows for grasses. Why is this happening? I thought dynamic shadows are calculated in real time, not pre-calculated…How can I solve this problem?? Thank you so much guys, I’ll be waiting online.