Comment 1 for bug 1791578

Reproduced with 18.04 standard AMI; confirmed bug not present in 16.04.
This file is written out by systemd-resolved, which was introduced between 16.04 and 18.04, which explains the change in behavior.

Here's the same issue being reported on CoreOS as well:
https://github.com/coreos/bugs/issues/1934

We are doing more research to see if there's a path forward to support this behavior, though there is some disagreement on what the correct behavior is here based on the DHCP spec.

We will continue to investigate and provide updates on this bug.