Why do I need to apply for TRV when I have my POST GRAD WORK PERMIT?
Work permit and TRV are two different things. I assumed you asked about TRV because that's what is put on your passport. If you want to extend your TRV, you must apply and pay the fees $100 - After your TRV application is approved (It will be since you've a valid PGWP) you have 30 days to send your passport to Ottawa so the TEV is stamped.
IRCC Website:
A work permit or study permit is not a visa.
We
won’t automatically issue you a visitor visa if you
extend your work or study permit. If you need a new visitor visa, you may need to submit a separate application.
You can apply for a visitor visa from inside Canada if you meet all the conditions below:
- you’re already in Canada
- you hold a valid study or work permit
- you want to leave and return to Canada in the near future
- your existing visitor visa is expired or was valid for only one entry
Good luck!