I had the same problem. It doesn't destroy my rocket, but it sends it into a violent rotation movement that completely ruins my ascent profile. I can recover from it after a few spins, but it annoys the heck out of me.
A member in a Twitch chat mentioned it could be related to physicsless parts. Apparently, if two physicsless parts are attached to one another, the transition between the two atmospheric levels at 21500 meter altitude creates a kraken force at that point - for me it's probably inside the fairing, which would explain the tumbling motion it sends my rocket into. I haven't yet figured out which two parts are the essential ones, so I cannot completely confirm the claim. For me it could be an antenna attached to a truss segment.
Edit: It definitely was the antenna connected to a truss segment. I attached the antennas directly to the outer hull of the craft and now the kraken strike doesn't happen anymore.
