We have used this same access code over multiple years w/o issue (and we have verified that it is as expected as seen on last year's NOA).

I understand that one can file w/o using the ACCESS CODE but as well there are implications filing one's return w/o one i.e. you will not be able to information on your 2020 tax return when confirming your identity with the CRA. You will have to rely on other information for authentication purposes.

I havent had time yet to call CRA (likely very difficult to reach someone) but I would imagine that they will say to file w/o it  :(. Frustrating.