No problems in J YYZ-LHR but I flew Y PHX-YYZ and it was almost full by the time I boarded with zone 4 which wasn't even 3/4 way through. So many were trying to find space after I was seated and failed to do so. I also recently flew YYZ-YYC-YVR-PHX and this time I boarded with one 2 so no issues for me but every single flight people had to gate check the carry on by the end. The YVR-PHX was the worst as it was an RJ... complete disaster

Almost every singe passenger had a carry on for all my recent AC flights.

Strange enough, I don't have this issue on AA or UA . I think people assume that AC will lose their luggage as there has been some horror stories so everyone switched to carry on only. Even the FOTSG's