Just my personal opinion: (do not rely on that, since it’s just my personal opinion, and I can be wrong)
If you renew your passport after submitting your application, while your application is under process, I personally believe that the photocopy of the old passport you send to IRCC with your application will not be valid anymore, because they won’t have your current valid identification document anymore. Hence, if you’re planning to renew your passport after your card will be issued, and your current passport remain valid until your new card is issued, you’ll be fine.
Do not renew your passport while your application is under process, because your old passport will be invalid and you’re putting your application at risk of being rejected easily, due to lack of valid identification documents.