There appears to be an issue with every appstream repository mirror I have tried.
errors on a fresh 8.6 install:
dnf update
AlmaLinux 8 - BaseOS 1.4 MB/s | 2.9 MB 00:02
AlmaLinux 8 - AppStream 252 kB/s | 9.1 MB 00:36
Errors during downloading metadata for repository 'appstream':
- Status code: 404 for http://syd.mirror.rackspace.com/almalinux/8.7/AppStream/x86_64/os/repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml (IP: 119.9.32.73)
- Curl error (28): Timeout was reached for http://mirror.dimensi.cloud/almalinux/8.7/AppStream/x86_64/os/repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml [Connection timed out after 30000 milliseconds]
- Status code: 404 for http://mirror.amscloud.co.id/almalinux/8.7/AppStream/x86_64/os/repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml (IP: 103.234.209.194)
- Status code: 404 for http://mirror.2degrees.nz/almalinux/8.7/AppStream/x86_64/os/repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml (IP: 202.36.220.86)
- Status code: 404 for https://dinosaurus.fleksibel.com/almalinux/8.7/AppStream/x86_64/os/repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml (IP: 43.252.136.5)
- Status code: 404 for https://ap.edge.kernel.org/almalinux/8.7/AppStream/x86_64/os/repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml (IP: 147.75.48.161)
- Status code: 404 for https://mirror.datamossa.io/almalinux/8.7/AppStream/x86_64/os/repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml (IP: 103.76.40.66)
- Status code: 404 for http://almalinux.mirror.digitalpacific.com.au/8.7/AppStream/x86_64/os/repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml (IP: 101.0.120.90)
- Status code: 404 for https://almalinux.ourhome.kiwi/8.7/AppStream/x86_64/os/repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml (IP: 172.67.195.86)
- Status code: 404 for http://kartolo.sby.datautama.net.id/almalinux/8.7/AppStream/x86_64/os/repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml (IP: 123.255.202.74)
Error: Failed to download metadata for repo 'appstream': Yum repo downloading error: Downloading error(s): repodata/6d41c28c03dbcf4af5d31e8549425c1615119da902ddcc433bff7658e5a875df-modules.yaml - Cannot download, all mirrors were already tried without success
I also receive the same errors on a fresh 8.7 install and on a known working 8.6 install at a different location.