The vyos-build/packages/telegraf/build.sh script has a hardcoded amd64 target:
echo "I: Build Debian amd64 package"
cd ${SRC}
export PATH=/opt/go/bin:$PATH
LDFLAGS=-w make amd64.debmake arm64.deb works fine on arm64
I found we can use BUILD_ARCH=$(dpkg-architecture -qDEB_TARGET_ARCH) as a neutral substitute
On arm64:
$ uname -m aarch64 $ dpkg-architecture -qDEB_TARGET_ARCH arm64
On x86-64:
$ uname -m x86_64 $ dpkg-architecture -qDEB_TARGET_ARCH amd64