Coinkite is telling Coldcard Mk3 owners to move funds off any seed generated on firmware from March 2021 onward, after researchers traced a 594 BTC sweep to what one investigator called flawed entropy in wallet generation. If true, the private key was never really private; it was guessable from the start, and the signature only proved you held a weak key, not a secret one. Randomness is not a detail. It is the whole lock.