Not only does cal in testing/sid no longer highlight today by default, it doesn't highlight at all. It doesn't really make sense for Debian to be the only major Linux distribution to nerf the cal binary in this way.
The version of cal in debian buster currently highlights the current
day. If anything, I would hope Debian would strive to maintain
compatibility with previous versions of Debian - instead of whatever
system the user #904839 may have been using.
