It depends on the airline you are arriving on. There is a list posted near the immigration area which tells you which airline passengers need to collect luggage and which don't.

I returned on LH about 2 weeks ago, with onward cxn on AC to SEA. I had to collect luggage, go thru Canada customs, and recheck for the AC flight then go through US pre-clearance. Due to this, several on the flight missed their connections to US even though most had two hours in between.

BTW, don't know if this is accurate but AC staff told me that airlines have to pay a fee to use the direct/transit transfer facility and LH doesn't want to do that.

I like YVR and have connected Intl many times via it but this hybrid setup is really confusing and definitely not planning to do another connection via YVR anytime soon.