Arch Linux Developers about the intention to enable support for the compression algorithm in the pacman package manager. Compared to the xz algorithm, using zstd will speed up the compression and decompression of packets while maintaining the level of compression. As a consequence, switching to zstd will lead to an increase in the speed of installing packages.
Support for compressing packets using zstd is coming in a release , but installing such packages will require a version of the libarchive with zstd support. Therefore, before distributing packages compressed with zstd, users are instructed to install at least version 3.3.3-1 of libarchive (the package with this version was prepared a year ago, so the correct release of libarchive is most likely already installed). Packages compressed by zstd will be shipped with the extension
".pkg.tar.zst".
Source: opennet.ru