Comment 8 for bug 1853164

For Ubuntu 20.04, resolvconf will not be allowed to manage /etc/resolv.conf, this will always be managed via systemd-resolved. So while you're right that this is a bug in the hook, it will not be a priority to fix since the code will be rewritten and replaced.

> Alongside this, systemd's often-buggy resolver can be disabled.

The vast majority of Ubuntu users are using systemd-resolved without incident or complaint. If you know of specific problems with it, we can best help you (and all other Ubuntu users) if you give us bug reports for those problems.