The 2021 re-released version, promoted as 4K remaster, is actually a terrible AI upscaled remaster based on the existing 2K restoration. The AI process was so badly done that many original details of the artwork was completely altered or destroyed. Sadly after this AI remaster, Shanghai Animation Studio decided to continue this AI up-scaling method and upscaled most of their works to 4K using AI based on previous HD restorations and became the only available version since.