After upgrading to sys-apps/util-linux-2.33-r1, I can no longer find a way to put literal backslash characters into /etc/issue properly. For many years, '\\' in the issue file would result in a single backslash being printed. I don't think this was ever documented; it's just the natural way to escape backslash as a special character. I guess the change is with agetty, but I don't know. Any ideas?
p.s.: Downgrading to util-linux-2.32-r4 got me the old behavior back.