The lower level of the cave behind the waterfall, near "Butcher Creek"

Guys, can you tell me who knows what, or maybe now you will learn something new.
Near the village "Butcher Creek" there is
a Spoiler-poisoned lake with a waterfall, behind the waterfall there is a hidden passage to the
Spoiler cave (spoiler * you will go through the mission plot there, so for those who have already completed the game it's not a secret).
So, in this very cave, if we move up from the lake, we will get to a place where the passage will be somewhat expanded, and from one of the edges there will be a gap down.
If you carefully go down into this gap, you can find a passage into which you can only squeeze on your haunches, and behind this passage the 2nd (lower) level of the cave opens.
If someone has not seen it , go and have a look , and those who have seen it , tell me , what is the meaning of this lower level ? Is there anything valuable or interesting in there? Or just developed for fun added?
*Upd- there is a small cave with a safe, but it is very close to the entrance, and the cave still stretches a lot.