I answered no when doing interactive upgrade check on 18.04 and this came up:
There are services installed on your system which need to be restarted when certain libraries, such as libpam, libc, and libssl, are upgraded. Since these restarts may cause interruptions of service for the system, you will normally be prompted on each upgrade for the list of services you wish to restart. You can choose this option to avoid being prompted; instead, all necessary restarts will be done for you automatically so you can avoid being asked questions on each library upgrade.
But wondering if this is now a global "no" for any upgrades, particularly security ones done by unattended-upgrades. I'm thinking of php 7.x for example - if that gets patched and not restarted, and it is broken, then php isn't running.
If php, apache, mysql etc. have their own postinst scripts that restart services and ignore my "no" then fine. If not, how do I reverse what I did?