What's causing this type of damage to the tyre?
It's a 25 x 622 tyre on a 13 x 622 rim.
Tyre is a Schwalbe Active Line K-Guard.
The tyre itself doesn't seem worn.
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It appears that the cords holding the body of the tire to the bead have torn. Overinflation, hitting a rock, curb, or other obstacle, running the tire at too low a pressure can cause such damage. I'm sure there are a host of other reasons as well.
It's also possible this tire was defective from the start. Hard to say at this point.