Note: https://hpiers.obspm.fr/iers/bul/bulc/README states:
# The files in this directory and sub directories are licensed under the Creative Commons Attribution 4.0 : CC BY-ND 4.0
# http://creativecommons.org/licenses/by/4.0/
which means it's 100% OK for our users to download it. This is the primary source and they have beefy servers.