A very simple Magisk module to disable phantom process killing at boot.
Probably not. The same can be achieved from Developer Options -> Disable child processes restrictions.
However, if you can't use developer options for any reason...
This Magisk module is incredibly simple and required little work to do.
All research about this Android feature was done by Github user agnostic-apollo here: https://github.com/agnostic-apollo/Android-Docs/blob/master/en/docs/apps/processes/phantom-cached-and-empty-processes.md