Shared libraries

This is not just a library issue either, it can also happen with data files or helper binaries that communicate via entirely different interfaces (e.g. browser tab helper processes).

Depending on the design of the program it might even happen if you make a config change and some more recently loaded part of the whole package (library, binary,...) reads the new configuration and the longer running parts use the old.

Sometimes that is even deliberate as part of some reload mechanism where a new binary loads a new config, then gets file handles for sockets and similar resources from the old binary so even using something like a snapshot of the filesystem from the time the first part of the package is started wouldn't be a universal solution.