Anyone familiar with this 3 pin optical liquid level sensor?

Unfortunately, I couldn't find any datasheet. I bought it thinking it was the 4 pin version. you can see the 4 pin version here, then the seller updated the listing (probably after I messaged them about that) with the 3 pin version. you can see it here, but I can't see anything useful.

I've asked the seller and I couldn't get anything useful.