Not "suddenly". Toxic, "Death Spiral" convertibles are and have always been BAD! That's why they are called "Toxic" and "Death Spirals".
Certain convertible securities, referred to as ‘toxic’ or ‘death spiral’ convertibles, permit the persons holding the convertible securities to engage in manipulative short selling of the issuer's stock in order to receive more shares at the time of conversion. Manipulators of this type rarely get away with such a scheme without collusive, stupid or desperate company owners