Sanders' deduction, although incorporating the two guesses of the Tree Spirit, is more convincing than a unilateral conclusion.
Because it has been confirmed that this knight's armor must have appeared in the ruins within the last century, the person who brought it here must have used a hidden passage that nobody knows about. Otherwise, if they entered through the main door, it would certainly trigger the sealing.
Since there is a hidden passage in this ruin, then it's not surprising that there could be hidden rooms as well.
The Tree Spirit pondered for a moment and looked at Sanders: "I agree with your deduction. However, the biggest question now is, where is this hidden passage to the outside world?"