Abnormal Water Generation

I am Errzinyle (stillabowlofstew on discord). I went into a random open world, spawned near a desert then fell through what I assume is quicksand. There was a cave below it, I went in there then saw water generating as if it were stone (?)

I do have mods, but given stonkyp1 saw it aswell I doubt it’s an issue on my end. I don’t know them, so I don’t think they’ve got mods.