dhcpcd-8.1.1 has been released with the following changes:

• IPv6: Fix a potential crash when udevs marks an interface ready.
• Linux: compat shim added for setproctitle(3).
• arc4random: fixed UB in compat shim.
• DHCP: Fix fallout from dhcpcd-8.1.0 for checksum calculation.

The last fix involved a lot a people, quite a few different fixes and played havoc with gcc-9.2 but should now be resolved.

ftp://roy.marples.name/pub/dhcpcd/dhcpcd-8.1.1.tar.xz
https://roy.marples.name/downloads/dhcpcd/dhcpcd-8.1.1.tar.xz