That right there is the infamous "Leaf of Death" . . .
Nah, it's probably a neat little mutation in your phenotype. It's kinda cool.
You should let us know if more appear.
I do have to ask though . . . Breeder and Cultivar????
Blueberry muffins f8 by humboldt seed company and haha that’s what I figured it was lol just was funny to me honestly I’ll post more if They pop up!