They know that the vfs are closed. I believe there was a tweet or official announcement that they would advise all applicants with ppr when vfs re-opens.But we have to inform IRCC that we are not able to submit our passport within 1 month... Then what step will be taken by IRCC?
In other words even if the letter says thirty days the extension should be automatic and you shouldn't worry. If you want to advise them of delay it won't hurt of course but the pause is global for the countries affected and they will deal with it.