The quest code appears to be PALINGENESIA for one version of the quest, and EALINGENESIA for another related/follow-up version in the same quest chain.

Which code to use

  • PALINGENESIA : shown in a guide for a fountain code entry.
  • EALINGENESIA : shown in another quest walkthrough for the fountain area.
  • A Reddit thread also confirms the fountain code is tied to the winter quest chapter and that the exact entry matters.

What this means

The most likely answer is that the quest you mean has a hidden code input, and the code depends on the chapter or route you chose.

The safest move is to try the code that matches your exact quest step, since the guides do not describe a single universal code for every version.

Extra note

Both sources describe the code being entered at a fountain or secret area in the quest, so this is not a general “quest code” for the whole game, but a specific puzzle code.