If you use the $arch token in the Path of your Installation Medium, the vmlinuz and initrd for an aarch64 host get pulled with the token interpolated as arm64 (because the Operatingsystem overrides boot_file_sources to pass a block that uses transform_vars), e.g. from

/pub/installation_media/ubuntu/22.04.3-arm64//casper/vmlinuz
/pub/installation_media/ubuntu/22.04.3-arm64//casper/initrd

but in, say, your image_path in the "Preseed default PXEGrub2 Autoinstall" template, which uses preseed_path, the token is left as aarch64, e.g.

/pub/installation_media/ubuntu/22.04.3-aarch64.iso

I imagine most people are not encountering this because the usual Debian/Ubuntu repository structure has a base path of simply /debian or /ubuntu that includes multiple releases, components, and arches (avoiding the need for tokens), and if you're creating custom Installation Media, e.g. as documented at https://docs.orcharhino.com/or/docs/sources/guides/ubuntu/provisioning_hosts/configuring_provisioning_resources.html#Creating_an_Installation_Medium_for_Ubuntu_22_04 (because Ubuntu stopped supplying boot images in the repository), then you might just put literal amd64 or arm64 in your Path like they tell you to, or if you didn't, you just rename the iso once you encounter the discrepancy.

However, in the interest of sparing others that surprise (and other potential surprises using custom Installation Media Paths), I think Foreman should use transform_vars on preseed_path also.