Automatic kernel removal does still not work --> softbricks system --> please prioritize

Dear contributors, sorry for opening a new Issue here. I feel it is necessary since it leads to softwarebrick especially for inexperienced / new LM users. This is very unfortunate, since they will go back to MS. Please prioritize
I am very thankful for your work, so please do not get me wrong.

Describe the bug
Old kernel keep accumulating until /boot/ is full even with "/Update Manager/Edit/Preferences/Automation Tab/delete old kernels" activated (should be default in my opinion)

The GUI will give a warning („Disk Usage Analyzer“). If no manual terminal Kung fu is known (only manual apt-get purge image... worked, no autoremove --purge, no apt-mark auto), this will lead to a system unable to update. In the case I supported a new user. The system was totally unusable (apt was broken).

The original issue: https://github.com/linuxmint/mintupdate/issues/938

Expected behavior
delete old kernel automatically leaving only the last two recent by default

Distribution:

• [ x] Linux Mint (see https://github.com/linuxmint/mintupdate/issues/938)
• [ x] LMDE (my case)
• Other (please specify)

Software version:
LMDE 7

Logs:
Copy & paste the log output from Update Manager > View > Information here.

Crash report:
If you are reporting a crash, please run mintupdate from a terminal window, reproduce the crash and copy & paste any output from the terminal window here.

Additional context
Add any other context about the problem you think might be relevant.

Locale:
If the problem is with text not getting displayed correctly, paste the output of the terminal command locale.

Start in Update Manager's Preferences > Automation tab with LMDE 7 and review the original issue #938 for related behavior. Reproduce the enabled old-kernel cleanup and verify that automation leaves only the two most recent kernels while /boot remains usable and updates continue.