@latein @RustyCrab @lina @jmw150 @Nudhul https://www.gnu.org/distros/common-distros.html#Arch

While the AUR is chock full of proprietary software, the default repository is chock full of proprietary software too;
https://archlinux.org/packages/core-testing/x86_64/linux/
https://archlinux.org/packages/core/any/linux-firmware/
https://archlinux.org/packages/extra/x86_64/nvidia/
https://archlinux.org/packages/core/any/amd-ucode/
https://archlinux.org/packages/extra/any/intel-ucode/
https://archlinux.org/packages/extra/x86_64/sof-firmware/

None of those packages have marking that signifies that they're proprietary, either putting "custom" as the license or even pretend that proprietary binaries are under a free software license.

Arch's default repository only offers proprietary versions of Linux, which alone makes Arch proprietary.

pacman doesn't have the ability to select accepted licenses either, thus it's very difficult to use Arch is freedom without accidentally installing proprietary software.