SUMMARY

Updates do not install on reboot, and there is no option to "press 'c' to cancel" during startup.

STEPS TO REPRODUCE
1. Boot machine
2. Receive pop-up notification that restart is needed to install updates
3. Restart
4a. Wait for reboot to complete
4b. Press arrow key (forget which one) to show detailed boot log
5. No option to "press 'c' to cancel updates" or anything like that come up for either the graphical boot or the detailed log view of the boot process
6. Return to step 2.

OBSERVED RESULT

Every time I boot the laptop, I get the same notification that I need to install updates.  In addition to the above steps, I have tried running `sudo apt update && sudo apt -y -m dist-upgrade && sudo apt -y autoremove && sudo apt -y autoclean` to try to freshly install the updates with no change in the outcome.

EXPECTED RESULT

Updates would install and stop notifying me.

SOFTWARE/OS VERSIONS
Windows: none
macOS: none
Kernel Version: 5.11.0.27-generic (64-bit)
(available in About System)
KDE Plasma Version: 5.22.5
KDE Frameworks Version: 5.85.0
Qt Version: 5.15.3
Processor: 4 x Intel Core i5-6200U CPU @ 2.30 GHz
Memory: 7.5 GiB of RAM
Graphics Processor: Mesa Intel HD Graphics 520

ADDITIONAL INFORMATION

I found bug 439909 (https://bugs.kde.org/show_bug.cgi?id=438809) describing a similar behavior but the listed solution do not work for me.  I do not get an option to press "c", I tried repeatedly pressing "c" anyway with no change.  I tried rebooting the machine over a dozen times with no change (Well over the three reboots described by Paul Worrall).