A clock drives an automatic package update, and a log records successful activity.

Question: How do I know unattended upgrades is running?
1 mindebianunattended-upgradesaptsecurityautomationsystem administrationupgradesunattendedconf

Answer

You should see logs in /var/log/unattended-upgrades/unattended-upgrades.log.

You also should have a /etc/apt/apt.conf.d/20auto-upgrades file:

apt_config 
APT::Periodic::Update-Package-Lists "1";
APT::Periodic::Unattended-Upgrade "1";

If yes, what does your 50unattended-upgrades file look like?

Mine looks like so (I don’t track -updates), add if needed. You’ll want to divert this file before you change it.

unattended_upgrades 
Unattended-Upgrade::Origins-Pattern {
  "origin=Debian,codename=${distro_codename},label=Debian";
  "origin=Debian,codename=${distro_codename},label=Debian-Security";
  "origin=Debian,codename=${distro_codename}-security,label=Debian-Security";
  "a=mozilla,n=mozilla";
  "o=Docker,a=bookworm";
  "o=Google LLC,a=stable,n=stable";
  "site=deb.nodesource.com";
  "site=updates.signal.org";
};

Unattended-Upgrade::Package-Blacklist {
};

Unattended-Upgrade::AutoFixInterruptedDpkg "true";
Unattended-Upgrade::MinimalSteps "true";
Unattended-Upgrade::InstallOnShutdown "false";
Unattended-Upgrade::Remove-New-Unused-Dependencies "true";
Unattended-Upgrade::Remove-Unused-Dependencies "true";
Unattended-Upgrade::SyslogEnable "true";

// Specify syslog facility. Default is daemon
// Unattended-Upgrade::SyslogFacility "daemon";

// Allow package downgrade if Pin-Priority exceeds 1000
Unattended-Upgrade::Allow-downgrade "true";

Please note that unattended-upgrades also allows you to override its config by placing a file in /etc/apt/apt.conf.d/99-unattended-upgrades (the 99 can be changed to any value > 50) and it will use that instead. I prefer the dpkg-divert.

In case you want to stop unattended-upgrades from even running you can set /etc/apt/apt.conf.d/20auto-upgrades to:

apt_config 
APT::Periodic::Update-Package-Lists "0";
APT::Periodic::Unattended-Upgrade "0";

or run dpkg-reconfigure unattented-upgrades, which will do the exact same thing or just remove the unattended-upgrades package completely.