Japan to US: Transit through YVR if "criminally inadmissible" for Canada entry

Hello, I am a US citizen and am, unfortunately, "criminally inadmissible" for entry to Canada due to my conviction history (30+ years ago but several convictions--all since expunged in US).

I have a layover/transfer in YVR (Vancouver, BC) on an upcoming trip from Japan to US. My understanding is that when traveling in the direction of US -> YVR -> Japan that it is necessary to pass through Canadian immigration at YVR and thus I cannot layover in Canada on my outbound flight.

However, I have read a few sources that indicate when traveling inbound from Japan -> YVR -> US, I will be immediately routed to US Customs/Immigration upon landing at YVR and will not contact Canadian immigration. This suggests I am fine to transit through YVR going this direction.

Does anyone here in the sub have insight into the process when transiting International to US through YVR? Thanks!

Edit: the Tokyo-YVR and YVR-US are on separate airlines.