Rooted Dirt From Azalea Trees Go Absurdly Low

I found an azalea tree an dug down. And down. And down. This tree must have had 200+ rooted dirt, as it went down to level 15 from 70.

Seed: -5375874480484831374
XYZ: -479 71 491

Interestingly, I provided another bug report on this as it was contained in a mushroom fields. Would this have any effect on it? Does this happen if an azalea tree appears in a mountain?