Git 2.21 introduces several significant updates, including improved human-readable date formats via the `--date=human` option, which provides a more intuitive understanding of commit dates compared to previous formats. The update also addresses case-insensitive path collisions during cloning by detecting and reporting colliding file groups, thus reducing confusion when using case-insensitive file systems. Performance enhancements include the introduction of multi-pack indexes, which optimize object storage without frequent repacking, and the concept of "delta islands," which helps in serving fetches more efficiently by avoiding cross-references between separate repository branches. Additional improvements such as delta reuse with reachability bitmaps and the optimization of custom alternate reference advertisements enhance the speed and efficiency of Git operations. Moreover, user experience is refined with progress indicators for commands like `git status` and the transition of key Git functionalities from shell scripts to C for improved performance.