Note: Canada Post’s Mail Forwarding Service does not forward parcels and a citizenship application package is considered a parcel. If we need to return your application package to you because it is incomplete, the package will be returned to us instead of being forwarded to the address you have indicated with Canada Post. If your application package is returned to us by Canada Post, it will not be processed.
I will suggest keeping an eye on your old address just in case, you can explain this to the landlord and he can escalate this with the new tenant. Give them your contact in case you have a return application.