Your sprites 3D model is too heavy typically due to high-resolution sprite textures, excessive sprite counts (e.g., crowded animations), or unoptimized 3D mesh geometry (unneeded polygons).
High-res textures (like 4K) take more memory, while too many sprites add cumulative data load—common in games using 2D sprites on 3D objects. Redundant polygons in meshes also bloat file size unnecessarily.
To reduce weight, resize textures to 1024x1024, remove duplicate sprites, or use tools like Blender to simplify meshes.