Does Xiamen International Airport requires visa for transit flight from Vancouver to Singapo

If the itinerary is, precisely:

Vancouver - Xiamen - Singapore

This itinerary is definitely eligible for visa free transit. It is eligible for both, 24 and 144 hour visa free transit in relation to the length of your layover. Of course, if your layover is longer than 24 hours, you will be eligible for 144 hour visa free transit, but your citizenship has to be among 53 eligible countries for this particular visa free transit scheme.

Please, have in mind that Malaysian citizens are not eligible for any kind of visa free transit scheme in China at the time being.

thank you.
The traveler is Indonesian citizen with Canadian Permanent Residency status. fyi
Another one is Canadian citizen.

So, keep in mind that your layover should be less than 24 hours because of an Indonesian citizen who is allowed for 24 hour visa free transit only. If your layover is less than 24 hours long, both of you will be eligible for 24 hour visa free transit and you don't need any kind of visa.