Comment 3 for bug 1915156

Yes, it looks like dpkg sets up the file to be tracked as part of snapd package.

$ dpkg -l snapd
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-==============-==============-============-============================================
ii snapd 2.45.1+20.04.2 amd64 Daemon and tooling that enable snap packages
$ dpkg -L snapd |grep sudoer
/etc/sudoers.d
/etc/sudoers.d/99-snapd.conf

$ apt upgrade snapd -y
...
$ dpkg -l snapd
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-==============-============-============-============================================
ii snapd 2.48.3+20.04 amd64 Daemon and tooling that enable snap packages
$ dpkg -L snapd|grep sudoe
/etc/sudoers.d/99-snapd.conf
<note /etc/sudoers.d is gone>

$ dpkg -S /etc/sudoers.d/99-snapd.conf
snapd: /etc/sudoers.d/99-snapd.conf

Now the fun part:

$ apt download snapd
$ dpkg -c snapd_2.48.3+20.04_amd64.deb | grep sudoers
<nothing>

Maybe we need to check whether anything can be done about this in the maintainer's scripts.