If you didn't receive a 1099-C, do not add the amount of the cancelled debt to other income. It isn't considered cancelled debt income until the issuer sends a Form 1099-C.
You may never receive a From 1099-C, in which case you'd be paying tax unnecessarily.
You may receive a Form 1099-C in 2021 (or even later), and you would have to report it as income in the year received.
