Employment status change

Client received CRA’s final ruling (CPP/EI) for his employment status.
As such, his status changed from self-employed to employed. Will the employer be required to issue a T4 and should I wait for it before Refiling his 2021 return (filed as self-employed).

The last time I fought one of those, CRA issued the revised T4 and charged the 'ee portion of CPP and EI to the employer.