UPDATE:Same here. I just noticed the same in my online portal but with the counterfoil document valid till 29th Dec of this year. My assumption is this is the visa stamp on your passport to enter Canada. Your COPR paper will come with the passport in the mail. When was your medicals reviewed? Technically, we should be getting validity of 1 year from medical review - correct? I think I am going to raise a webform to see if I can get an extension as well because my medicals were reviewed in April, 2022.
I did send out a webform to IRCC, but of course did not hear back to that request. BUT, IRCC CPC sent me an email that my FEDEX envelope did not have a return commercial invoice (for crossing into US, apparently I needed to include that). So, I just filled and sent a PDF over email to them of a return commercial invoice. But I also, added a note in my email to extend my counterfoil validity to April 2023 (since my medicals were reviewed in April 2022). And today, I saw some activity on the return tracking that Fedex received the package so looks like they dispatched it. Nillow, not sure if they have updated the counterfoil validity per my request. So, i'll keep you posted when I get the passports.
NOTE: The online portal says 29th Dec, 2022 as the counterfoil validity.