Forever? I don't think I've ever seen a Xiaomi phone with IC certification. That's why you've never seen them sold at Canadian providers, or other 'legitimate' sources.
There was the beginnings of a crackdown a year or two ago, here is a thread that discussed it:
Seems that eBay Canada is allowing listings again, or at least, not removing them.
Whatever government entity pushing eBay Canada probably gave notice to Ali and GB that they'd block import.