Hi, why this has expired without any confirmation/non-confirmation? This sounds like a terrible way to resolve bugs?!

I just had the same on a pretty vanilla 20.04 server which kernel was/is compiled Nov 13 11:40:37 UTC 2020.

below command returns nothing:
apt-config dump | grep Reboot

also:
fgrep -i reboot /etc/apt/apt.conf.d/50unattended-upgrades 
// Automatically reboot *WITHOUT CONFIRMATION* if
//  the file /var/run/reboot-required is found after the upgrade
//Unattended-Upgrade::Automatic-Reboot "false";
// Automatically reboot even if there are users currently logged in
// when Unattended-Upgrade::Automatic-Reboot is set to true
//Unattended-Upgrade::Automatic-Reboot-WithUsers "true";
// If automatic reboot is enabled and needed, reboot at the specific
//Unattended-Upgrade::Automatic-Reboot-Time "02:00";


The only way I found out about this reboot was by looking into /var/log/syslog
Mar  5 12:57:44 ip-192-168-141-181 systemd[1]: unattended-upgrades.service: Succeeded.


After reboot I see packages are still pending so unlikely have updated anything:

The following NEW packages will be installed:
  amd64-microcode intel-microcode iucode-tool linux-aws-headers-5.4.0-1038 linux-headers-5.4.0-1038-aws linux-image-5.4.0-1038-aws linux-modules-5.4.0-1038-aws microcode-initrd python3-pexpect python3-ptyprocess
The following packages will be upgraded:
  alsa-ucm-conf apt apt-utils base-files bind9-dnsutils bind9-host bind9-libs bolt bsdutils busybox-initramfs busybox-static cloud-init containerd cryptsetup cryptsetup-bin cryptsetup-initramfs cryptsetup-run dirmngr docker.io ec2-hibinit-agent ec2-instance-connect
  fdisk finalrd friendly-recovery gnupg gnupg-l10n gnupg-utils gpg gpg-agent gpg-wks-client gpg-wks-server gpgconf gpgsm gpgv grub-common grub-pc grub-pc-bin grub2-common initramfs-tools initramfs-tools-bin initramfs-tools-core jq language-selector-common
  libapt-pkg6.0 libasound2 libasound2-data libblkid1 libc-bin libc6 libcryptsetup12 libdrm-common libdrm2 libefiboot1 libefivar1 libfdisk1 libglib2.0-0 libglib2.0-bin libglib2.0-data libjq1 libmount1 libnetplan0 libnss-systemd libpam-systemd libparted2 libplymouth5
  libruby2.7 libsmartcols1 libsystemd0 libudev1 libuuid1 linux-aws linux-headers-aws linux-image-aws locales lshw lsof mdadm motd-news-config mount netplan.io open-vm-tools parted plymouth plymouth-theme-ubuntu-text pollinate python-apt-common python3-apt
  python3-distupgrade python3-software-properties python3-twisted python3-twisted-bin python3-update-manager ruby2.7 software-properties-common sosreport systemd systemd-sysv systemd-timesyncd ubuntu-release-upgrader-core udev update-manager-core
  update-notifier-common util-linux uuid-runtime zlib1g
105 upgraded, 10 newly installed, 0 to remove and 0 not upgraded.
Need to get 142 MB of archives.
After this operation, 172 MB of additional disk space will be used.

/var/log/dpkg.log empty today (05-Mar-2021)
latest entries
2021-02-26 06:04:04 trigproc install-info:amd64 6.7.0.dfsg.2-5 <none>
2021-02-26 06:04:04 status half-configured install-info:amd64 6.7.0.dfsg.2-5
2021-02-26 06:04:04 status installed install-info:amd64 6.7.0.dfsg.2-5
2021-02-26 06:04:04 trigproc systemd:amd64 245.4-4ubuntu3.2 <none>
2021-02-26 06:04:04 status half-configured systemd:amd64 245.4-4ubuntu3.2
2021-02-26 06:04:04 status installed systemd:amd64 245.4-4ubuntu3.2


unattended-upgrades-shutdown.log latest entry in 2020-10-20 
unattended-upgrades-dpkg.log 2021-02-26 

unattended-upgrades.log:
2021-03-05 05:50:36,537 INFO Starting unattended upgrades script
2021-03-05 05:50:36,538 INFO Allowed origins are: o=Ubuntu,a=focal, o=Ubuntu,a=focal-security, o=UbuntuESMApps,a=focal-apps-security, o=UbuntuESM,a=focal-infra-security
2021-03-05 05:50:36,538 INFO Initial blacklist: 
2021-03-05 05:50:36,538 INFO Initial whitelist (not strict): 
2021-03-05 05:50:38,646 WARNING package linux-aws upgradable but fails to be marked for upgrade (E:Unable to correct problems, you have held broken packages.)
2021-03-05 06:13:35,658 INFO Starting unattended upgrades script
2021-03-05 06:13:35,659 INFO Allowed origins are: o=Ubuntu,a=focal, o=Ubuntu,a=focal-security, o=UbuntuESMApps,a=focal-apps-security, o=UbuntuESM,a=focal-infra-security
2021-03-05 06:13:35,659 INFO Initial blacklist: 
2021-03-05 06:13:35,659 INFO Initial whitelist (not strict): 
2021-03-05 06:13:37,940 WARNING package linux-aws upgradable but fails to be marked for upgrade (E:Unable to correct problems, you have held broken packages.)
2021-03-05 06:13:40,008 INFO No packages found that can be upgraded unattended and no pending auto-removals
2021-03-05 06:13:40,189 INFO Package linux-aws is kept back because a related package is kept back or due to local apt_preferences(5).
2021-03-05 06:13:40,194 INFO Package linux-headers-aws is kept back because a related package is kept back or due to local apt_preferences(5).
2021-03-05 06:13:40,197 INFO Package linux-image-aws is kept back because a related package is kept back or due to local apt_preferences(5).