I just thought, i would share my experience and knowledge regarding PR card photos so that it's helpful for others to avoid getting photo request.
First , let me share the link for photo specifications on CIC website which also gives examples of photos accepted and common mistakes.
https://www.canada.ca/en/immigration-refugees-citizenship/services/new-immigrants/pr-card/apply-renew-replace/photo.html
In my case, I took my photos from within Canada by professionals as per specification (they have ready template). The photos were all good and yet i received photo request after waiting more than 2 months.I asked the agents over phone and got to know the photos are read/rejected by machine and there is no reason noted on file usually.
I went again to take the photos to same place and told them that my earlier photo got rejected and asked them to be extra careful this time..
This time the photographer took extra effort to make sure photos were as per specifications and that's when I was told that since my skin is oily and I have buzz cut, even though there were no background reflections, there was some light reflection coming from my face and edges where hair line met. It's something you have to look very carefully to notice.. May be these reflections were the reason for photos rejected first time.
Finally after applying some powder (matte) and few retakes/prints , they photos were much better..and 2 months later , my PR card was approved yesterday
So, folks with oily skin, or bald head etc take extra measure to make sure your photos have no reflections on them on top of meeting all other specifications in above CIC link. This precaution will save you couple of months of delay, effort and money. Good Luck to all!