Comment 25 for bug 1877633

I am not sure how packages.ubuntu.com generates its list but they were published for all architectures on launchpad: https://launchpad.net/ubuntu/+source/libseccomp/2.4.3-1ubuntu3.20.04.2

Also the debs are present on ports.ubuntu.com: http://ports.ubuntu.com/ubuntu-ports/pool/main/libs/libseccomp/libseccomp-dev_2.4.3-1ubuntu3.20.04.2_armhf.deb and listed in the focal-security Packages.gz as expected.

So I suspect this is some artefact of packages.ubuntu.com perhaps only taking into account the contents of the security / updates pocket on amd64/i386 - but again I am not certain. However as far as apt is concerned, these packages exist and should be installed automatically by unattended-upgrades etc.